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Writing SECURITY DEFINER Functions SafelyManual ChaptersPG18Writing SECURITY DEFINER Functions Safely Because a SECURITY DEFINER function is executed with the privileges of the user that owns it, care is needed to ensure that the function cannot be m…Writing SECURITY DEFINER Functions Safely Writing Trigger Functions in CManual ChaptersPG1837.3. Writing Trigger Functions in C This section describes the low-level details of the interface to a trigger function. This information is only needed when writing trigger functions in C.…Writing Trigger Functions in C XML FunctionsManual ChaptersPG189.15. XML Functions The functions and function-like expressions described in this section operate on values of type xml. See Section 8.13 for information about the xml type. The function-lik…XML Functions XML Limits and Conformance to SQL/XMLManual ChaptersPG18D.3. XML Limits and Conformance to SQL/XML Significant revisions to the XML-related specifications in ISO/IEC 9075-14 (SQL/XML) were introduced with SQL:2006. PostgreSQL's implementation of …XML Limits and Conformance to SQL/XML XML PredicatesManual ChaptersPG189.15.2. XML Predicates The expressions described in this section check properties of xml values.XML Predicates XML TypeManual ChaptersPG188.13. XML Type The xml data type can be used to store XML data. Its advantage over storing XML data in a text field is that it checks the input values for well-formedness, and there are supp…XML Type xml2 — XPath querying and XSLT functionalityManual ChaptersPG18F.50. xml2 — XPath querying and XSLT functionality The xml2 module provides XPath querying and XSLT functionality.xml2 — XPath querying and XSLT functionality xml_is_well_formedManual ChaptersPG189.15.2.4. xml_is_well_formed xml_is_well_formed ( text ) → boolean xml_is_well_formed_document ( text ) → boolean xml_is_well_formed_content ( text ) → boolean These functions check whether …xml_is_well_formed xmlaggManual ChaptersPG189.15.1.8. xmlagg xmlagg ( xml ) → xml The function xmlagg is, unlike the other functions described here, an aggregate function. It concatenates the input values to the aggregate function cal…xmlagg xmlcommentManual ChaptersPG189.15.1.2. xmlcomment xmlcomment ( text ) → xml The function xmlcomment creates an XML value containing an XML comment with the specified text as content. The text cannot contain “--” or end …xmlcomment xmlconcatManual ChaptersPG189.15.1.3. xmlconcat xmlconcat ( xml [, ...] ) → xml The function xmlconcat concatenates a list of individual XML values to create a single value containing an XML content fragment. Null valu…xmlconcat xmlelementManual ChaptersPG189.15.1.4. xmlelement xmlelement ( NAME name [, XMLATTRIBUTES ( attvalue [ AS attname ] [, ...] ) ] [, content [, ...]] ) → xml The xmlelement expression produces an XML element with the give…xmlelement XMLEXISTSManual ChaptersPG189.15.2.3. XMLEXISTS XMLEXISTS ( text PASSING [BY {REF|VALUE}] xml [BY {REF|VALUE}] ) → boolean The function xmlexists evaluates an XPath 1.0 expression (the first argument), with the passed …XMLEXISTS xmlforestManual ChaptersPG189.15.1.5. xmlforest xmlforest ( content [ AS name ] [, ...] ) → xml The xmlforest expression produces an XML forest (sequence) of elements using the given names and content. As for xmlelemen…xmlforest xmlpiManual ChaptersPG189.15.1.6. xmlpi xmlpi ( NAME name [, content ] ) → xml The xmlpi expression creates an XML processing instruction. As for xmlelement, the name must be a simple identifier, while the content …xmlpi xmlrootManual ChaptersPG189.15.1.7. xmlroot xmlroot ( xml, VERSION {text|NO VALUE} [, STANDALONE {YES|NO|NO VALUE} ] ) → xml The xmlroot expression alters the properties of the root node of an XML value. If a version…xmlroot xmltableManual ChaptersPG189.15.3.3. xmltable XMLTABLE ( [ XMLNAMESPACES ( namespace_uri AS namespace_name [, ...] ), ] row_expression PASSING [BY {REF|VALUE}] document_expression [BY {REF|VALUE}] COLUMNS name { type …xmltable xmltextManual ChaptersPG189.15.1.1. xmltext xmltext ( text ) → xml The function xmltext returns an XML value with a single text node containing the input argument as its content. Predefined entities like ampersand (&…xmltext xpathManual ChaptersPG189.15.3.1. xpath xpath ( xpath text, xml xml [, nsarray text[] ] ) → xml[] The function xpath evaluates the XPath 1.0 expression xpath (given as text) against the XML value xml. It returns an…xpath xpath_existsManual ChaptersPG189.15.3.2. xpath_exists xpath_exists ( xpath text, xml xml [, nsarray text[] ] ) → boolean The function xpath_exists is a specialized form of the xpath function. Instead of returning the indi…xpath_exists xpath_tableManual ChaptersPG18F.50.3. xpath_table xpath_table(text key, text document, text relation, text xpaths, text criteria) returns setof record xpath_table is a table function that evaluates a set of XPath queries…xpath_table XSLT FunctionsManual ChaptersPG18F.50.4. XSLT Functions The following functions are available if libxslt is installed:XSLT Functions xslt_processManual ChaptersPG18F.50.4.1. xslt_process xslt_process(text document, text stylesheet, text paramlist) returns text This function applies the XSL stylesheet to the document and returns the transformed result. …xslt_process Zero-Column TablesManual ChaptersPG18Zero-Column Tables PostgreSQL allows a table of no columns to be created (for example, CREATE TABLE foo();). This is an extension from the SQL standard, which does not allow zero-column tabl…Zero-Column Tables “All-the-Same” Inner TuplesManual ChaptersPG1865.3.4.3. “All-the-Same” Inner Tuples The SP-GiST core can override the results of the operator class's picksplit function when picksplit fails to divide the supplied leaf values into at lea…“All-the-Same” Inner Tuples