Virtuoso Functions Guide

Function: VAR

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Returns the variance.VAR (VARIANCE) returns variance of expr. Virtuoso calculates the variance of expr as follows: 0 if the number of rows in expr = 1; VAR_SAMP if the number of rows in expr > 1

Function: VAR_SAMP

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Returns the sample variance.VAR_SAMP returns the sample variance of a set of numbers after discarding the nulls in this set. The expr is a numeric expression, and the function returns a value of type NUMERIC. If the function is applied to an empty set, then it returns null. The function makes the following calculation: This function is similar to VAR, except that given an input set of one element, VAR returns 0 and VAR_SAMP returns null.

Function: VAR_POP

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Returns the population variance.VAR_POP returns the population variance of a set of numbers after discarding the nulls in this set. The expr is a number expression, and the function returns a value of type NUMERIC. If the function is applied to an empty set, then it returns null. The function makes the following calculation:

Function: STDDEV

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Returns the standard deviation.STDDEV returns standard deviation. it returns STDDEV_SAMP if the number of pairs is more than one, or NULL.

Function: STDDEV_SAMP

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Returns the cumulative sample standard deviation.STDDEV_SAMP computes the cumulative sample standard deviation and returns the square root of the sample variance. The expr is a numeric expression, and the function returns a value of type NUMERIC. This function is same as the square root of the VAR_SAMP function. When VAR_SAMP returns null, this function returns null.

Function: STDDEV_POP

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Returns the population standard deviation.STDDEV_POP computes the population standard deviation and returns the square root of the population variance. This function is the same as the square root of the VAR_POP function. When VAR_POP returns null, this function returns null.

Function: REGR_SYY

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Auxiliary function used to compute various diagnostic statistics.REGR_SYY makes the following computation after eliminating NULL (expr1, expr2) pairs:

Function: REGR_SXX

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Auxiliary function used to compute various diagnostic statistics.REGR_SXX makes the following computation after eliminating NULL (expr1, expr2) pairs:

Function: REGR_SXY

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Auxiliary function used to compute various diagnostic statistics.REGR_SXY makes the following computation after eliminating NULL (expr1, expr2) pairs:

Function: REGR_AVGX

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Evaluates the average of the independent variable (expr2) of the regression line.REGR_AVGX evaluates the average of the independent variable (expr2) of the regression line. It makes the following computation after the elimination of null (expr1, expr2) pairs:

Function: REGR_AVGY

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Evaluates the average of the independent variable (expr1) of the regression line.REGR_AVGY evaluates the average of the independent variable (expr1) of the regression line. It makes the following computation after the elimination of null (expr1, expr2) pairs:

Function: REGR_R2

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Returns the coefficient of determination (R-squared) of the regression line.REGR_R2 returns the coefficient of determination (also called "R-squared" or "goodness of fit") for the regression. VAR_POP(expr1) and VAR_POP(expr2) are evaluated after the elimination of null pairs. The return values are:

Function: REGR_COUNT

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Returns the number of non-null numbers used to fit the regression line.REGR_COUNT Returns the number of non-null numbers used to fit the regression line.

Function: REGR_INTERCEPT

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Returns the y-intercept of the regression line.REGR_INTERCEPT returns the y-intercept of the regression line. After the elimination of null (expr1, expr2) pairs, it makes the following computation:

Function: REGR_SLOPE

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Returns the slope of the line.REGR_SLOPE returns the slope of the line. After the elimination of null (expr1, expr2) pairs, it makes the following computation:

Function: COVAR_SAMP

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Returns the sample covariance of a set of number pairs.COVAR_SAMP returns the sample covariance of a set of number pairs. Both expr1 and expr2 are numeric expressions. Virtuoso applies the function to the set of (expr1, expr2) pairs after eliminating all pairs for which either expr1 or expr2 is null. Then Virtuoso makes the following computation: where n is the number of (expr1, expr2) pairs where neither expr1 nor expr2 is null.

Function: COVAR_POP

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Returns the population covariance of a set of number pairs.COVAR_POP returns the population covariance of a set of number pairs. Both expr1 and expr2 are numeric expressions. Virtuoso applies the function to the set of (expr1, expr2) pairs after eliminating all pairs for which either expr1 or expr2 is null. Then Virtuoso makes the following computation: where n is the number of (expr1, expr2) pairs where neither expr1 nor expr2 is null.

Function: CORR

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Returns the coefficient of correlation of a set of number pairs.CORR returns the coefficient of correlation of a set of number pairs. Both expr1 and expr2 are number expressions. Virtuoso applies the function to the set of (expr1, expr2) after eliminating the pairs for which either expr1 or expr2 is null. Then Virtuoso makes the following computation:

Function: abs

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Return the absolute value of a numberabs returns the absolute value of its argument.

Function: __any_grants

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Checks a table for grants.The __any_grants() can be used to test whether there are any rights granted (for insert/update/delete) to a table for current SQL account.

Function: aref

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns specific element of an array or stringaref returns the nth element of an array, string or string_session, where nth is a zero-based index. If the first argument is a string or string_session, the integer ASCII value of the nth character is returned. If the first argument is an array of any, then the corresponding element is returned.

Function: ascii

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Get ASCII value of a characterascii returns the ASCII value of the first character of a string. If an empty string is given, then zero is returned.

Function: aset

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

set array elementaset sets the nth element of a string, array or vector where nth is a zero-based index. If the first argument is a string, the nth character of string is replaced with the ASCII value given in the third argument elem.

Function: atof

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Convert a string to single precision floatatof returns its argument as a single precision floating point. If the string cannot be parsed and converted to a valid float, a value 0.0 is returned.

Function: atoi

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Convert a string to an integeratoi returns its argument as an integer. If the string cannot be parsed and converted to a valid integer, a value 0 is returned.

Function: att_local_name

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Compose a fully qualified table name based on DSN and remote table name.The utility function, att_local_name(), can be used to make a fully qualified table name from non-qualified or qualified one, i.e. the qualifier and owner will be added if they are missing. The schema name will be replaced with current qualifier on execution, owner will be replaced or added with name of supplied DSN name. All non-alphanumeric characters in the name will be replaced with underscore symbol.

Function: backup

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Write data into transaction log format for backup purposes. Deprecated. This function requires dba privileges.

Function: backup_online

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

perform online backup of databaseThis procedure will backup all information from the checkpoint space to a series of files named ".bp", where is the sequence number of the file in the backup series. The first backup will be a full gzip compressed dump of database pages in the checkpoint space. Any subsequent call will only backup pages which have changed since the last backup was made. To start with a fresh full backup, use backup_clear_context to clear the change tracking data. At each checkpoint the checkpoint space will be updated, and the next "backup_online;" procedure will create new files. Once backup_online() has been called for the first time, the arguments supplied will be used for subsequent calls to it. Hence, arguments supplied to this procedure (except the "dirs" argument) will be ignored in subsequent calls. Before a new backup series can be started, the backup_context_clear(); procedure must be called first. This procedure will clear the current backup context and mark all pages in the checkpoint space as ready for backup. A database checkpoint cannnot be performed while an online backup is in progress. Attempt to do a checkpoint will wait until the backup is complete.

Function: backup_context_clear

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Clears the backup context and marks all pages in checkpoint space as ready for online backupThis procedure must be called before a new backup series can be started, This procedure will clear the current backup context and mark all pages in the checkpoint space as ready for backup.

Function: Virtuoso Server Extension Interface (VSEI) functions

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Get parameters for built in functionThe bif_...._arg functions are used in the Virtuoso shared object. They allow customization of the Virtuoso server. They are written in C code, and linked with the Virtuoso shared object. The _or_null_ variants of these functions represent the SQL null value as a 00 pointer, even though getting the same argument with bif_arg() would return a box with the DV_DB_NULL tag. All number functions will coerce other types of numbers to the result type. All array argument functions will accept any type of array. It is up to the VSE itself to distinguish. Virtuoso Server Extensions (VSEs) were formally referred to as Built-In Functions (BIFs).

Function: bit_and

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Returns bitwise AND of two 32-bit integers.The function returns bitwise AND of two given integers. On 64-bit platforms, both arguments are intentionally truncated to 32 bits to maintain compatibility.

Function: bit_or

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Returns bitwise OR of two 32-bit integers.The function returns bitwise OR of two given integers. On 64-bit platforms, both arguments are intentionally truncated to 32 bits to maintain compatibility.

Function: bit_not

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Returns bitwise NOT of a 32-bit integer.The function returns bitwise NOT of a given integer. On 64-bit platforms the argument is intentionally truncated to 32 bits to maintain compatibility.

Function: bit_shift

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Returns the result of bitwise shift operation over two 32-bit integers.The function returns bitwise shift of two given integers. Depending on the arguments, the shift may be left or right. For right-shift, leftmost bits of the result are filled by the value of the 31-st bit. On 64-bit platforms, both arguments are intentionally truncated to 32 bits and the shift is restricted to 32 bits to maintain compatibility.

Function: bit_xor

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Returns bitwise XOR (exclusive "or") of two 32-bit integers.The function returns bitwise XOR (exclusive "or") of two given integers. On 64-bit platforms, both arguments are intentionally truncated to 32 bits, to provide compartibility.

Function: blob_to_string

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Convert a blob to stringAlthough primarily used for converting blobs (long varbinary, long varchar) to string, blob_to_string may also be used to convert from wide string, persistent XML (XPER) and string_output streams. If the data being converted is longer than maximum length of a string, blob_to_string will signal an error.

Function: blob_to_string_output

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Convert a blob to string sessionAlthough primarily used for converting blobs (long varbinary, long varchar) to string output object, blob_to_string_output may also be used to convert from wide string, persistent XML (XPER) and string_output streams.

Function: bookmark

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Return the bookmark for current row of a scrollable cursorbookmark returns a bookmark for the current row of an open scrollable cursor. Given an invalid argument, i.e. no cursor, no current row or non-open cursor, it signals an error. The returned value can be used in subsequent FETCH .. BOOKMARK over the same cursor.

Function: ceiling

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Round a number to positive infinity.ceiling calculates the smallest integer greater than or equal to x.

Function: cfg_item_count

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

return number of items in a section in configuration fileReturn the number of items that exist in the specified section of the INI file.

Function: cfg_item_name

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

get nth item name from ini fileReturns the name of the item specified by item_index (begins from zero). If the index and section name do not point to a valid item, then zero is returned, otherwise on success the function returns the item name.

Function: cfg_item_value

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns the value of an item from the ini fileReturn the value of an item identified by item_name and section parameters from the specified INI file.

Function: cfg_section_count

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

get number of sections in an INI fileReturns the number of sections in an INI file.

Function: cfg_section_name

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns INI file section nameReturns the name of section specified by the index (begins from zero). If the index can reference a section, the that section name is returned, otherwise returns zero on error.

Function: cfg_write

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Writes the item=value to an INI fileThis function requires dba privileges. This function allows modification of existing entries, or update updating existing items in an INI file.

Function: charset_define

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Define a character set.This function creates a new narrow language-specific character set, or redefines an existing one.

Function: charset_recode

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Translate a string to another character setThis function translates a string from a given source charset to a destination charset. It provides a generic way of recoding string entities. The src_charset may be a narrow or a wide string. If it's a narrow string (VARCHAR) then the src_charset is taken into account and defines the current encoding of the src_string. In any other case src_charset is ignored. src_charset and dst_charset are names of system-defined 8 bit charset tables. Use charsets_list to obtain a list of currently defined character sets and aliases. If either of these is null, then the charset in effect is used. There are two special character set names - "UTF-8" and "_WIDE_" - that are recognized by this function. These represent UTF-8 encoding of characters and wide string (NVARCHAR).

Function: charsets_list

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

List known character set names and aliases.This function produces a list of all character set names and aliases known to Virtuoso. The returned value is an array of strings with a character set name as each element. If the gen_res_set flag is 1, the function also produces a result set in which each row contains one varchar column with a name of a character set or alias.

Function: checkpoint_interval

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Configure database checkpointingThis function changes the database checkpointing interval to the given value in minutes. It may also be used to disable checkpointing in two ways: By setting checkpoint interval to 0, the checkpoint will only be performed after roll forward upon database startup. A setting of -1 will disable all checkpointing. Main use for this function is to ensure a clean online backup of the database slices. Copying of the database may take long and checkpointing would modify those files in mid-copy, thus rendering the resulting copy unusable. In case the system should, for some reason or another, become unstable, it is sometimes better to disable checkpointing after a database restart to resume backing up from where it was left prior to a system crash. Disabling all checkpointing by giving checkpoint_interval the value of -1 will do just that. The interval setting will be saved in the server configuration file as value of CheckpointInterval in section [Parameters], thus it will persist over consecutive server shutdown/restart cycles. A long checkpoint_interval setting will produce longer transaction logs, which in turn prolongs the time it takes for the database to perform a roll forward upon restart in case it was shut down without making a checkpoint.

Function: chr

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Convert a long character code to a character or wide characterchr returns a new one character long string containing the character with character code given as parameter.

Function: client_attr

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns a varchar containing the requested information from the connection

Function: collation_define

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

define a new collationThis function lets you define a new collation.

Function: complete_table_name

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Returns a fully qualified table name.The complete_table_name() can be used to make a fully qualified table name from non-qualified one, i.e. the qualifier and owner will be added if they are missing.

Function: composite

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

create a composite objectCreate a composite object Returns a composite object containing the serialization of each argument. The total serialized length of the arguments may not exceed 255.

Function: composite_ref

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

get member of a composite objectcomposite_ref returns the nth element of the composite. The index is 0 based.

Function: concat

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Concatenate stringsconcat returns a new string, concatenated from a variable number of strings given as arguments. NULL arguments are handled as empty strings. concat (str) returns a copy of str. concat () returns an empty string.

Function: concatenate

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

concatenate stringsConcatenate is an alias of concat.

Function: connection_get

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Get connection variableconnection_get is used to retrieve values stored within the current connection context. See connection_set for a more detailed discussion of connection variables.

Function: connection_id

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

get connection identifierThis function returns a string uniquely identifying the connection in this server instance. It is usually a combination of server's port number and a serial number of the client.

Function: connection_is_dirty

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

check if current session connection variables have been alteredThis function is used to determine if the session variables have changed between a call to connection_vars_set and current point of execution. A call to connection_vars_set will cause subsequent calls to connection_is_dirty to return true. The function is useful in postprocessing functions for making conditional storage of session variables in a database table.

Function: connection_set

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Associates a value to the name in the context of the present connectionThis associates a value to the name in the context of present connection. The name should be a string and the value can be any data type except blob, open cursor or an XML entity. If the value is an array it may not contain the restricted types. Connection variable setting is not logged and information stored will be lost when the connection is closed. The value can be retrieved by any future statement executing within the same connection. Connection variables can be used as a global variable mechanism for stored procedures, the scope being the client connection. In the case of VSP or SOAP this mechanism cannot be used to pass information between requests by the same client. It will however, be useful for having 'global variables' between procedures called within the same HTTP request. Note that this mechanism is used to provide persistent HTTP session variables in some cases but this works through special before and after code which stores the values set with this function into an external session structure. In this sense this function itself has nothing to do with web session management although it can be used as a component for such.

Function: connection_vars

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Retrieve all connection variables This function returns all stored session variables in an array with name/value pairs. Connection variables do not persist across sessions, one may maintain persistence of variables by storing them in a database table: see the Session Variables Section.

Function: connection_vars_set

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

set all connection variablesThis function clears all connection variables for current session and sets new ones defined in the array passed as parameter. Connection variables do not persist across sessions, one may maintain persistence of variables by storing them in a database table, as discussed in Session Variables -section.

Function: contains

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

A text contains predicate This is a SQL predicate that specifies a condition on a column on which a free text index exists. The expression is a string matching the grammar of a text search expression. This is computed for each evaluation of the contains predicate and does not have to be a constant. For example a parameter or variable of a containing score (e.g. procedure) is accepted. The score_limit is optional. If specified, it should be a numeric expression determining the minimum score required to produce a hit. A virtual column named 'SCORE' is available in queries involving a contains predicate. This can for example be returned in a result set or used for sorting. Note that the name is in upper case and is case sensitive in all case modes.

Function: cov_load

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Load test coverage data from file.This function accepts one argument with name of file containing test coverage data. The expected format of the file is described in the Branch Coverage section. The loaded file is merged with the data already collected by Virtuoso. More than one file can be loaded. The ultimate report will be the union of all files.

Function: cov_report

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Produce a text coverage report.This function is used to produce a coverage report in text format. The format of the file is described in the Branch Coverage section. This function takes a filename 'fname' as a path to the extended coverage report file and 'outdir' as a path to a directory where .cov files will be stored. The profile.prof file in the output directory is a summary of function call counts and execution times, once ranked by self time, once by time spent inside the function and functions called from there. Note that directory must exists before calling this function.

Function: cov_store

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Writes a test coverage to a file.This function is used to produce a coverage file called fname. The expected format of the file is described in the Branch Coverage section. By default a normal concise coverage will be produced. If the add_comment parameter is set to 1 then the coverage will include code excerpts contained in line entities.

Function: createXML

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

This function creates an XMLType instance. It works absolutely identically to the XMLType() constructor and is provided solely for compatibility.

Function: curdate

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

get current date and timeThese functions return the current date or time as a date, time or datetime, respectively. Internally they all return the same value but data type reported to client differs.

Function: current_charset

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Get name of current charset.This function returns the "preferred" name of the current charset as a string. It returns value which is set in the INI file or those which is set with 'SET CHARSET=..' call. This cannot be used to return charset for the current HTTP connection in the VSP or VSPX context.

Function: DB.DBA.VACUUM

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Compact the databaseThis function reads through the specified tables and indices and finds groups of adjacent pages holding data that will fit on fewer pages than it currently occupies. If such a compression can be made, the pages are thus compacted. The pages become part of the committed state and will be written to the checkpoint space on the next checkpoint. The vacuum operation is non-locking and can be run on a busy database. It will simply skip pages with ongoing activity such as pending cursors or locks. The vacuum procedure returns only after it has read through the indices it affects but it will not prevent other activity on the indices. The vacuum operation may run out of disk space even if it makes net gains because the modified pages will not be final until the next checkpoint and the originals will not be free until this same checkpoint. Thus manually running a checkpoint after vacuum runs out of space will free the space and vacuum may be rerun.

Function: dateadd

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

arithmetic add to a datedateadd adds a positive or negative quantity of units to a date (in the internal date time format), and returns a new date so formed. The unit is specified as a string and can be one of the following: 'second', 'minute', 'hour', 'day', 'month', or 'year'. Use datestring to convert the result to a human-readable string.

Function: datediff

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

get difference of 2 datesdatediff subtracts date1 from date2 and returns the difference as an integer in the specified units.

Function: datestring, datestring_gmt,

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

convert a datetime from internal to external date-time representationdatestring and datestring_gmt convert timestamps or datetimes from internal to external date-time representation. The external representation is a human-readable ASCII string of up to 30 characters. The external format is: YYYY-MM-DD hh:mm:ss uuuuuu where uuuuuu represents microseconds.

Function: datestring_GMT

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

convert a timestamp to external format string in GMTConverts the local datetime to GMT and returns its external representation as a string.

Function: DAV add & update functions

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

functions for adding, updating, deleting of DAV collections or resourcesDAV_COL_CREATE creates a new collection on path, with supplied security permissions, returning a collection id (COL_ID) upon success. DAV_RES_UPLOAD creates or replaces an existing resource on path with content, mime type and supplied security permissions. Returns a resource id (RES_ID) on success. DAV_DELETE Removes an existing collection/resource. If silent is set to a nonzero value, no errors codes will be returned. returns 1 on success.

Function: DAV manipulation functions

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Functions for manipulating an existing DAV collection or resourceDAV_COPY copies the resource or collection taken from path to the destination. returns COL_ID or RES_ID on success. DAV_MOVE moves the collection or resource to the destination path returns 1 on success. DAV_PROP_SET defines or updates the property with name propname with propvalue. Returns PROP_ID on success.

Function: DAV lock manipulation functions

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Operations on locks of DAV collections and resourcesDAV_LOCK sets a new lock or refresh an existing lock or creates a lock object. DAV_UNLOCK releases a lock. DAV_IS_LOCKED reports whether the resource or collection is locked.

Function: DAV search functions

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Functions for searching a DAV collection or resourceDAV_SEARCH_ID() returns the RES_ID or COL_ID, depending on the 'what' parameter passed. ('R'esource or 'C'ollection or 'P'arent collection). DAV_SEARCH_PATH() returns full path string of resource or collection, depending on parameter passed. ('R'esource or 'C'ollection or 'P'arent collection). DAV_DIR_LIST() returns an array of arrays that contains the following information about the requested path:

Function: WebDAV Users & Groups administration

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Functions for manipulating an existing DAV collection or resourceDAV_ADD_USER() create a new WebDAV user with login name 'uid' and password 'pwd'. User will belong to the group named 'gid'. 'perms' are the default user permissions for creation of new resources. Additional user info supplied is 'home' directory, 'full name' and 'e-mail'. DAV_DELETE_USER() remove the existing webDAV user named 'uid'. DAV_HOME_DIR() returns the home folder for specified WebDAV user named 'uid'.

Function: DAV_EXP

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Export a retrieved Web site to another WebDAV enabled serverThis function is used to export local content retrieved from a Web Robot Copy to the local file system.

Function: dayname

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

decompose a datetime to its componentsThese functions decompose a datetime to its components. These can be used on timestamps, datetimes, dates and times, all being the same internal data type.

Function: dayofmonth

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

get day of month from a datetimedayofmonth takes a datetime and returns an integer containing day of the month represented by the datetime

Function: dayofweek

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

get day of week from a datetimedayofweek takes a datetime and returns an integer containing a number representing the day of week of the datetime.

Function: dayofyear

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

get day of year from a datetimedayofyear takes a datetime and returns an integer containing a number representing the day of year of the datetime.

Function: dbg_obj_print

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

print to the Virtuoso system consoledbg_obj_print prints a variable number of arguments onto the system console (stdout) of Virtuoso server, each argument in its own native format, on the same line, which is followed by one newline.

Function: dbg_printf

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

print formatted output onto the system consoledbg_printf prints a variable number (max. eight) of arguments to the system console of Virtuoso server, each argument formatted in C printf style, according to the format string specified in the first argument.

Function: dbname

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

get current catalogReturns the current qualifier as set by the USE statement or default.

Function: delay

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

sleep for n secondsThis will halt calling procedure execution for specified interval in seconds.

Function: dict_duplicate

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Creates a copy of the given dictionary.The function creates a full copy of the given dictionary. Dictionary objects are always passed by reference, even if dictionary is passed as an 'in' argument of a function. If value of a variable is a dictionary and it is assigned to other variable then both variables refer to the same internal hash table. This function returns a really independent dictionary object. This function duplicates the given dictionary but does not duplicate dictionaries that may be stored in key-value pairs.

Function: dict_get

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Returns the dependent part that corresponds to the given key in the given dictionary.The function returns the dependent part that corresponds to the given key in the given dictionary. The function returns default_value if the dictionary does not contain a pair whose key is equivalent to the given one. When only two arguments are passed to the function the default value is integer zero.

Function: dict_list_keys

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Returns an array of all keys stored in the given dictionary.The function returns an array of all keys stored in the given dictionary, ignoring dependent parts of key-value pairs. This is especially useful when dictionary is used to form a set of dictinct keys, when dependent parts are fake (typically zeroes). If the destructive parameter is nonzero then the function may avoid copying of keys to the resulting array by moving them out from the dictionary. This is faster but the dictionary will become empty at the end of operation. The destructive parameter does not have any effect if the dictionary is used as a value of more than one variable. Thus it is safe to make this parameter nonzero as soon as the variable passed to the function as dict is no longer in use after the function call and there's no need to inspect the whole program to check if other variables may be affected.

Function: dict_new

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Creates a new dictionary to store key-value pairs.This function creates a new dictionary. A dictionary is a memory-resident hash table that can store an arbitrary number of key-value pairs. Both key and dependent part can be of any type, including vectors. Two keys of different data types are always considered as different even if SQL '=' operator return 'true', e.g. integer zero and double precision 0.0 are two different keys. Vectors are equivalent if their corresponding members are either equal scalars or equivalent vectors. XML entities are equivalent if they refer to the same node or attribute in the same document. Dictionary objects are always passed by reference, even if dictionary is passed as an 'in' argument of a function. If value of a variable is a dictionary and it is assigned to other variable then both variables refer to the same internal hashtable. To create two really independent dictionary objects, use dict_duplicate ().

Function: dict_put

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Adds a key-value pair to a dictionaryThe function adds or updates a key-value pair in the given dictionary. If the dictionary contains a pair with the key part equivalent to the given one then old value is replaced with a new one. Otherwise, a new pair is added to the dictionary.

Function: dict_remove

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Removes the given key and associated dependent value from the given dictionary.The function removes the given key and the associated dependent value from the given dictionary. If the key-value pair is found (and removed) the function returns 1. If the dictionary does not contain a key equivalent to the given one the function returns zero.

Function: dict_to_vector

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Returns a get_keyword style vector of all items stored in the given dictionary.The function returns an array of all data stored in the given dictionary, every pair is represented as two consecutive element of the resulting array. Thus the dictionary of N pairs is converted into a vector of length 2N where keys are at positions 0, 2, 4, ..., 2N-1 and corresponding dependent data are at positions 1, 3, 5, ..., 2N. If keys are all scalars of same type then get_keyword function can be used to search in the resulting array. If the destructive parameter is nonzero then the function may avoid copying of keys to the resulting array by moving them out from the dictionary. This is faster but the dictionary will become empty at the end of the operation. The destructive parameter does not have any effect if the dictionary is used as a value of more than one variable. Thus it is safe to make this parameter nonzero as soon as the variable passed to the function as dict is no longer in use after the function call and there's no need to inspect the whole program to check if other variables may be affected.

Function: disconnect_user

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Disconnect client connections of a given userdisconnect_user disconnects clients whose username matches the username_pattern string given as an argument, and returns an integer value giving the number of clients disconnected. This can be used after DELETE USER or REVOKE statement to make sure that the affected user has no open connections.

Function: dt_set_tz

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

modifies the timezone component of a datetimeThis modifies the timezone component of a datetime. The value remains equal for purposes of comparison but will look different when converted to a string. The timezone component is an offset from UTC in minutes. It can be retrieved with the timezone function.

Function: dvector

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

return an array of either long, float or double These functions are like vector but return an array of either long, float or double whereas vector returns a generic, untyped array.

Function: end_result

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

End the current result set.The result_names() predefines variables to be used in a result set to follow. The variables must be previously declared, from which the column data types are ascertained. This assigns the meta data but does not send any results. The result() function sends its parameters as a single row of results. These parameters should be compatible with those in the previous result_names(). The end_result() function can be used to separate multiple result sets. The result_names() can then be used to alter the result set structure. The result_names() call can be omitted if the application already knows what columns and their types are to be returned.

Function: either

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

conditionally return one of specified parameterseither returns a copy of arg1 if cond is something else than integer 0 (zero). Otherwise, a copy of arg2 is returned.

Function: elh_get_handler

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

get localization function handler

Function: elh_load_handler

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

load encoding handler into system Loads given handler in table of handlers bound to encoding specified in the handler, using ISO 639 and RFC 1766 language IDs of the handler as keys for future table lookups. If another handler was already specified for given RFC 1766 id, table entry will be updated and will refer to new handler. If another handler was already specified for given ISO 639 id, it will be replaced only if new handler has ISO 639 language ID equal to its RFC 1766 ID. Please do not load custom versions of 'x-any' and 'x-ftq-x-any' handlers.

Function: encode_base64

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

base64-encode/decode a stringThese functions convert strings from/to base64-encoding.

Function: equ

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

comparison functionsThese functions return 1 if their first argument is less than (lt), less than or equivalent (lte), greater than (gt), greater than or equivalent (gte), equivalent (equ), or not equivalent (neq) to the second argument, respectively. If the arguments are not of the same type, then an appropriate type coercion is done for them before comparison. These functions correspond to SQL query operators <, <=, >, >=, = and <> and are needed because the SQL syntax does not allow these operators to be used on the left side of FROM keyword in a SELECT statement.

Function: exec

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

dynamic execution of SQL returning state and result setThis function provides dynamic SQL capabilities in Virtuoso PL. The first argument is an arbitrary SQL statement, which may contain parameter placeholders. The function returns as output parameters a SQL state, error message, column metadata and result set rows if the statement is a select. A stored procedure can be invoked by exec but a procedure's result set will not be received in the rows output parameter but rather sent to the client.

Function: close

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Closes cursor created by exec()Closes the cursor opened by the exec() function.

Function: exec_next

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Get next result from a result setUse exec_next() to iterate over a result set produced by a statement run with exec.

Function: exec_result

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Returns a result set row to the calling procedure contextThis function returns a result set row to the calling procedure's context, whether it is the client, exec function or a procedure view). The row's values are the elements of the supplied res_values_array vector.

Function: exec_result_names

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Supplies column details for procedure result set output.This function allows you to define the column details for result sets returned by procedures, in particular for use with the exec() function. This function is similar to result_names().

Function: exec_metadata

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Compiles a SQL statement and returns the metadataThis function provides dynamic SQL capabilities in Virtuoso PL. The first argument is an arbitrary SQL statement, which may contain parameter placeholders. The function returns as output parameters a SQL state, error message, column metadata if the statement is a select.

Function: exec_score

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Compiles a SQL statement and returns the estimate time costThis function provides dynamic SQL capabilities in Virtuoso PL. The first argument is an arbitrary SQL statement, which may contain parameter placeholders. The function returns as output parameters a SQL state, error message and returns the estimate time cost in milliseconds.

Function: exp

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

calculate exponentThe function raises e to the power of x, it works with double precision floating point numbers, converts its argument to an IEEE 64-bit float and returns a result of that type.

Function: explain

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

describe SQL statement compilation The explain function compiles a SQL statement and returns a description of that compilation as a result set, return value or parse tree. The result set consists of one VARCHAR column with one line of the description in each row. Any given line may be quite long, even several hundred characters. The output is not a complete disassembly of the query graph, but it is detailed enough to show the join order, the sub-query structure, and the order of evaluation of query predicates, as well as the splitting of a distributed VDB query over different data sources. The optional cursor type can be one of the SQL_CURSOR_ constants, or one of the special values listed below. The default is 0, for FORWARD ONLY. The special values each have special effect, as listed. If the statement is a SELECT and the cursor type is not FORWARD ONLY, the auxiliary SQL statements used by the cursor implementation are shown.

Function: file_delete

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Delete a file from the file systemThis function requires dba privileges. This function is used to delete a file from file system. This function has a silent mode, where no errors will be signalled upon failure.

Function: file_dirlist

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Returns list with content of file system directoryThis function requires dba privileges. This returns the list of the contents of a given file system directory.

Function: file_mkdir

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Creates a directory in the file systemThis function requires dba privileges. This function creates a file system directory.

Function: file_mkpath

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Make a directory chainThis function requires dba privileges. This is to create a directory chain i.e. 'a/b/c/d', where one or more elements in the path may not exist.

Function: file_stat

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

get various OS statistics about a filefile_stat returns various information for an OS file by calling stat () system call and converting the relevant value to a varchar. The path is relative to the server's working directory. The what is an integer value selecting what information to return. If you don't supply second argument to the function it defaults to mode = 0. The DirsAllowed and DirsDenied lists in Parameters section of the virtuoso configuration file (virtuoso.ini by default) are not used to control disk access.

Function: file_to_string

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns the contents of a file as a varcharThis function requires dba privileges. Returns the contents of a file as a varchar value. The file's length is limited to 16 MB. The path is relative to the working directory of the database server.

Function: file_to_string_output

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

get contents of a file as a string output streamThis function requires dba privileges. This function returns a string output stream initialized to contain the text of the file or its segment, on local file system path relative to the server's working directory. file_to_string_output can handle longer files than file_to_string and the resulting string output, if too long to be converted into a varchar, can be stored inside a blob.

Function: file_unlink

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Delete a file from the file systemThis function requires dba privileges. This function deletes a file from the file system. sys_unlink is a synonym of this function.

Function: fk_check_input_values

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

alter default foreign key checking behavior Enforcing foreign key constraints is enabled by default. This function allows globally disabling it without however disabling all triggers. This may be useful for large data imports or other special circumstances. The return value is the previous state of this setting, 0 for off, 1, for on. The effect of this function is persistent and survives server restart.

Function: floor

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Round a number to negative infinity.floor calculates the largest integer smaller than or equal to x.

Function: ftp_get

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

FTP get command; Virtuoso FTP clientVirtuoso has FTP client functionality, that can be used inside Virtuoso/PL. This Virtuoso function mimics the FTP get command. As with any PL, this can be combined with Web Services and SOAP.

Function: ftp_ls

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

FTP dir command; Virtuoso FTP clientVirtuoso has FTP client functionality, that can be used inside Virtuoso/PL. This Virtuoso function mimics the FTP dir command. As with any PL, this can be combined with Web Services and SOAP.

Function: ftp_put

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

FTP put command; Virtuoso FTP clientVirtuoso has FTP client functionality, that can be used inside Virtuoso/PL. This Virtuoso function mimics the FTP put command. As with any PL, this can be combined with Web Services and SOAP.

Function: get_certificate_info

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Returns information about the current client X509 certificate This function will return information about the current client X509 certificate (if successfully verified). If there is no valid X509 certificate or the requested information is not available it will return NULL. If the optional cert_or_key_name is supplied it should contain a encoded certificate (by default format is PEM). The certificate info is read from the first certificate in that string. If the optional cert_or_key_name is supplied and in_format is equal to 3 (integer) the function will try to retrieve the certificate registered in the current user's key store by name contained in cert_or_key_name.

Function: get_keyword

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Find a value in keyword vectorget_keyword performs a case sensitive seek for the occurrence of keyword from each even position of searched_array. If found,this returns the element following the occurrence of the keyword. If the keyword is not found this returns the default argument or NULL if the default is not supplied.

Function: get_keyword_ucase

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Find a value in keyword vector (search uppercase)Identical to get_keyword except all comparisons are performed case insensitively.

Function: get_timestamp

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns the timestamp of the current transactionget_timestamp is merely an alias for now and is provided for backward compatibility.

Function: getdate

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns the current transaction timestamp, alias of nowgetdate() returns the timestamp associated with current transaction. This is an alias of now().

Function: gz_compress

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Compress data using gzip algorithm The gz_compress returns its argument compressed with the gzip algorithm. The argument and return values are arbitrary strings, possibly including any 8 bit characters.

Function: gz_uncompress

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Uncompress a string using gzip algorithmgz_uncompress takes a string argument, uncompresses it using the gzip algorithm, writing it to a string_output given as the second argument.

Function: hour

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

get hour from a datetimehour takes a datetime and returns an integer containing a number representing the hour of the datetime.

Function: http

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

write to HTTP client or a string output streamhttp writes val_expr to HTTP client or, if parameter stream is given, to the given string output stream. val_expr may be any scalar object, i.e. string, date or number and will automatically be cast to varchar before further processing. http will print out the string without escapes. http_value uses HTML escapes and http_url URL escapes.

Function: http_acl_get

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Test conditions against web server ACL'sThis function can be used within application logic to test that an internet client would not violate the ACL.

Function: http_body_read

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Reads the HTTP body from the client HTTP connection and returns it as a string. This function reads the HTTP body from the client HTTP connection and returns it as a string output. This is suitable for processing POST requests with bodies encoded differently than multipart/* and application/x-www-form-urlencoded as in SOAP requests where the POST body is encoded as text/xml).

Function: http_client

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns a varchar containing the body of the request uriThis function is used to perform HTTP operations to retrieve generic content and/or to perform generic operations over HTTP/HTTPS protocols. It also supports HTTP authentication based on username/password credentials. If the URL is https: an no x509 certificate given then it will operate as https client w/o client certificate.

Function: http_client_ip

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Returns the IP address of the calling client.This function is used to determine the IP address or DNS name of the calling client. Please note that this function is slow when resolving a DNS names. It is advisable to use IP addresses to to make applications faster.

Function: http_debug_log

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

set WebDAV HTTP request loggingWhen an valid path string is supplied and it is allowed in file ACL list, the WebDAV HTTP requests and responses will be logged in append mode in to that file. When an open logging session is encountered the second call will produce an error. Specifying a NULL instead of file_path string stops the logging. The log file consists of lines with following fields:

Function: http_enable_gz

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Enable / Disable "Content-Encoding: gzip" for HTTP server Enable (1)/ Disable (0) "Content-Encoding: gzip" for HTTP server.

Function: http_file

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Send a file to the HTTP client This function causes the contents of the file specified by path to be sent as the response of the calling request. The file is not sent until the code calling this returns. Content types etc. are defaulted based on the file's extension. If this function is called, other output to the HTTP client by the caller is discarded.

Function: http_flush

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Flush internal HTTP stream and disconnect client; Flush HTTP stream and try sending data in chunked mode. This flushes the internal buffer where output of a VSP page is stored pending the execution of the page's code. This sends the content of the page output buffer along with headers and disconnects the client. The status is 200 OK by default, unless overridden by http_status. The purpose of this function is to allow a page to send output before terminating , thus the page can continue processing for an indefinite time without requiring the client to wait. This is useful for starting long running background tasks from HTTP clients. VSP pages that use this function must be sure to supply appropriate content (or response headers) if needed before calling this function. Virtuoso supports HTTP 1.1 Chunking Encoding which allows Virtuoso to send the user agent chunks of output as the page is still processing. Chunking is enabled by calling http_flush(1) within the VSP page. By default chunks are sent for every 4k worth of output generated, but in some cases the output needs to consist of smaller chunks, for example when run-time status needs to be shown in a status page. So to achieve this the http_flush (try_what=1) could be invoked in places where chunk must be flushed to the User agent.

Function: http_get

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns a varchar containing the body of the request urihttp_get returns a varchar containing the body of the requested target_uri or NULL if the body is not received.

Function: http_header

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Specifies non-default HTTP response headers This function is used to add additional HTTP header lines to the server response. The http_header parameter MUST finish with characters. Warning: Each call of this function cancels the effect of the previous call. In order to add to previously set header lines, use the http_header_get function to retrieve the current headers. A Content-Type or Media-Type header specified as a part of the headers given with this function will override the default. Otherwise the header lines set using this function add to but do not replace the default response headers. Note that this function cannot set the status line. Use http_request_status for that.

Function: http_header_get

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns header of current HTTP request Returns the response header associated with the current HTTP request. This will not return the default header lines, only those explicitly set with http_header. This is useful for incrementally modifying response headers during processing of a URL.

Function: http_kill

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Kill VSP process whose details match parameter inputsThis function requires dba privileges. This function is used to kill the process whose details match that of the input parameters. If Client's IP and URL are specified, then it will try to kill all matching pending HTTP requests for that peer requesting that URL. If all three parameters are given, then it will try to kill only that pending HTTP request.

Function: http_listen_host

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Starts, stops and retrieves the state of a user-defined HTTP listenerThis function requires dba privileges. This function is used to start, stop or lookup the state of user-defined HTTP and HTTPS listeners. The return value is 0 or 1 and indicates state of the listener, 1 for started and 0 for stopped.

Function: http_map_table

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Update internal HTTP mapping tableThis function requires dba privileges. This function inserts an entry defining a virtual directory into the HTTP maps table.

Function: http_map_get

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

get values from HTTP virtual host path mapping table Retrieves information associated with the virtual host / HTTP path mapping in effect for the VSP page being processed. Values valid in current connection or URL context may be retrieved by element_name. Calling http_map_get has no use outside of http context. In this case an error will be signalled.

Function: http_param

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns value of a HTML form parameter in VSP contextThis function is used to return value of a HTML form parameter in VSP context. It's almost like call get_keyword ('name', params) used in VSP programming. When 'name' parameter is not supplied, the result of http_param() call will be all parameters, as they are contained in 'params' parameter of the VSP pages. This function is useful in HTTP authentication PL hook, as in this place there is no 'params' argument.

Function: http_path

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns the absolute path to the logical path location of the current http request This function returns the absolute path to the logical path location of current HTTP request.

Function: http_pending_req

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

return array describing running VSP threadsThis function requires dba privileges. http_pending_req returns an array of arrays of data on running VSP requests. Each array contains the Client IP Address, URL, and Process Request ID. These values can be used with the http_kill() function.

Function: http_physical_path

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns the physical path location of the requested URL This function returns the absolute path to the physical path location of current HTTP request

Function: http_proxy

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

proxy request to another host and return content to calling client This function is used to retrieve content from a foreign host and send the response to the HTTP client of the page calling this. This is useful for re-routing a request to another server in the middle of a VSP page.

Function: http_request_header

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns array of HTTP request header lines This function provides access to the HTTP request header lines.

Function: http_request_status

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

set the status sent to the client in an HTTP response This allows a VSP page to control the status sent to the client in the HTTP response. The argument will be presented as the first line of the reply instead of the default "HTTP/1.1 200 OK". The string should not contain a CR or LF at the end. This allows a page to issue redirects, authentication challenges etc. Use it with http_headers to control the content of the HTTP reply headers.

Function: http_request_get

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Access to the HTTP request line This function is used to access the HTTP request line within VSP or VSPX context. It returns 'CGI' style variables for protocol version, HTTP method and query string.

Function: http_rewrite

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Clears output written to a string output or to an HTTP This clears any previous output to the stream. If the stream is omitted or 0 the stream is the HTTP client stream of the calling procedure. All output from VSP page procedures is buffered into a local string stream before being sent out. This is done so as to support the HTTP/1.1 required content length and to allow recovery from errors.

Function: http_root

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Returns the absolute path of the server root directory.

Function: http_value

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

write to HTTP client or string output stream with HTML escapesThe http_value is used to write to an HTTP client (when in a VSP context) or a specified string output stream. http_value uses HTML-escapes for characters that should be escaped according to the HTML spec.

Function: http_url

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

write to HTTP client or string output stream with URL escapesThe http_url is used to write to an HTTP client (when in a VSP context) or a specified string output stream. http_url uses URL escapes for special characters.

Function: http_xslt

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

applies an XSLT stylesheet to the output of a VSP page This function can be called inside a VSP page to apply an XSLT stylesheet to the output of the page once the page is complete. This function will return immediately and the stylesheet will not be applied until the page is successfully formed. Any errors arising in the stylesheet processing will be reported to the web client. The stylesheet does not have to be previously defined. The URI supplied will be used to locate the stylesheet. This can be a file, an HTTP URL or a virt:// URI for a stylesheet stored in a local table. Virtuoso will cache the stylesheet after first use. You can clear the cache entry with the xslt_stale() function. For this to work the text generated by the VSP page should be well-formed XML.

Function: URLREWRITE_CREATE_REGEX_RULE

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Creates regex rules.

Function: identity_value

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns the last assigned identity column valueThis function returns the value assigned to an identity column by the previous insert statement. Insert statements that do not assign identity columns do not affect this. Note that tables that have no primary key have n invisible identity column called _IDN. The scope is the connection. This function may be called from a client or from a stored procedure and will return the last given identity column value wherever it was given. The value stays set until overwritten by the next insert operation. This value is not set by rexecute or inserts to remote tables with autoincrement columns declared on the remote database since there is no standard way of getting this information from remote data sources. The same value can be more efficiently accessed from clients using the SQLGetStmtOption ODBC call with the option SQL_GETLASTSERIAL. In this case the value is of type SQLINTEGER.

Function: import_clr

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

This function automatically creates the SQL Type wrappers based on the CLR Reflection API.This function automatically creates the SQL Type wrappers based on the CLR Reflection API.

Function: import_jar

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Creates SQL wrapper types of selected Java classesThis function calls the jvm_ref_import() function to produce the XML, then transforms it to a set of CREATE TYPE statements and executes them. The SQL names of the types are generated by retrieving the fully qualified name of the Java class and substituting the . with _ (e.g.: java.lang.System becomes java_lang_System). The names of the static members observer functions are composed by prepending the name of the static member with 'get' so the static Java member stat_m is mapped to a SQL static method getstat_m(). As a result it creates SQL type wrappers for the specified Java classes.

Function: initcap

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns its argument with the first letter capitalizedinitcap returns a copy of string str with the first character, if it is a lowercase letter, converted to the corresponding uppercase letter. Otherwise, an identical copy of the string is returned. Notes about ucase apply also here.

Function: internal_to_sql_type

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns the integer standard SQL type of its argumentinternal_to_sql_type returns an integer value representing the standard SQL type converted from internal_type given as its argument.

Function: internal_type

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns internal integer datatype of its argumentinternal_type returns an integer value representing the internal type of its argument. These values are the same as what Virtuoso uses in the column COL_DTP of the system table SYS_COLS for keeping the track of the default types of each column of each table.

Function: internal_type_name

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns the internal type name of the argumentinternal_type_name returns a string which is a human-readable name for an internal_type integer given as its argument. The function dv_type_title() is an alias of internal_type_name().

Function: isarray

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Check for a valid arrayisarray is true if the argument is a valid argument to aref. This is the case for any string or vector.

Function: isblob

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns true if its argument is of type long varcharisblob returns one if its argument as a handle to an object of the type LONG VARCHAR, zero otherwise.

Function: isbinary

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns true if its argument is of type varbinaryisbinary returns one if its argument is of type VARBINARY, zero otherwise.

Function: isdouble

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns true is argument is a double isdouble returns one if its argument is of type double precision float, zero otherwise.

Function: isentity

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns true if its argument is an XML entityisentity is true if the argument is an XML entity object, such as that returned from XPATH expressions etc.

Function: isfloat

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns true if its argument is a floatisfloat returns one if its argument is of type single float, zero otherwise.

Function: isinteger

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns true if its argument is of type integerisinteger returns one if its argument is of type integer, zero otherwise.

Function: isnull

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns true if its argument is NULLisnull returns one if its argument is NULL, zero otherwise.

Function: isnumeric

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns true if argument is of numeric typeisnumeric returns one if its argument is of type integer, single float or double precision floating point number, zero otherwise.

Function: isstring

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns true if its argument is of type varcharisstring returns one if its argument is of type VARCHAR, zero otherwise.

Function: iszero

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

returns true if argument is numeric zero iszero returns one if its argument is an integer 0, a float 0.0 or a double 0.0 For any other arguments, of whatever type, it will return zero.

Function: java_call_method

virtuoso.docs@openlinksw.com — Sun, 12 Oct 2008 02:08:44 GMT

Calls a class method using the supplied parameters (if any) and returns the return value (if any). If instance_obj is supplied (not NULL) then this function searches for a non-static method otherwise for static.