explain root element for auto-explain - Mailing list pgsql-hackers

The attached tiny patch sets the <explain> root element for auto-explain
XML output, so it looks something like this:

    <explain xmlns="http://www.postgresql.org/2009/explain">
      <Plan>
        <Node-Type>Result</Node-Type>
        <Startup-Cost>0.00</Startup-Cost>
        <Total-Cost>0.01</Total-Cost>
        <Plan-Rows>1</Plan-Rows>
        <Plan-Width>0</Plan-Width>
      </Plan>
    </explain>

The JSON output looks like this:

    [
      "Plan": {
        "Node Type": "Result",
        "Startup Cost": 0.00,
        "Total Cost": 0.01,
        "Plan Rows": 1,
        "Plan Width": 0
      }
    ]

This is worth doing in itself in the XML case for reasons previously
explained, but it also makes it relatively easy to add a Query-Text node
or some such to the structured output, which is very much worth having,
and would be my next proposed step.

cheers

andrew
Index: contrib/auto_explain/auto_explain.c
===================================================================
RCS file: /cvsroot/pgsql/contrib/auto_explain/auto_explain.c,v
retrieving revision 1.7
diff -c -r1.7 auto_explain.c
*** contrib/auto_explain/auto_explain.c    10 Aug 2009 05:46:49 -0000    1.7
--- contrib/auto_explain/auto_explain.c    17 Aug 2009 21:19:08 -0000
***************
*** 222,228 ****
--- 222,230 ----
              es.verbose = auto_explain_log_verbose;
              es.format = auto_explain_log_format;

+             ExplainBeginOutput(&es);
              ExplainPrintPlan(&es, queryDesc);
+             ExplainEndOutput(&es);

              /* Remove last line break */
              if (es.str->len > 0 && es.str->data[es.str->len - 1] == '\n')
Index: src/backend/commands/explain.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/commands/explain.c,v
retrieving revision 1.189
diff -c -r1.189 explain.c
*** src/backend/commands/explain.c    10 Aug 2009 05:46:50 -0000    1.189
--- src/backend/commands/explain.c    17 Aug 2009 21:19:09 -0000
***************
*** 91,98 ****
                   bool labeled, ExplainState *es);
  static void ExplainDummyGroup(const char *objtype, const char *labelname,
                                ExplainState *es);
- static void ExplainBeginOutput(ExplainState *es);
- static void ExplainEndOutput(ExplainState *es);
  static void ExplainXMLTag(const char *tagname, int flags, ExplainState *es);
  static void ExplainJSONLineEnding(ExplainState *es);
  static void escape_json(StringInfo buf, const char *str);
--- 91,96 ----
***************
*** 1712,1718 ****
   * This is just enough different from processing a subgroup that we need
   * a separate pair of subroutines.
   */
! static void
  ExplainBeginOutput(ExplainState *es)
  {
      switch (es->format)
--- 1710,1716 ----
   * This is just enough different from processing a subgroup that we need
   * a separate pair of subroutines.
   */
! void
  ExplainBeginOutput(ExplainState *es)
  {
      switch (es->format)
***************
*** 1739,1745 ****
  /*
   * Emit the end-of-output boilerplate.
   */
! static void
  ExplainEndOutput(ExplainState *es)
  {
      switch (es->format)
--- 1737,1743 ----
  /*
   * Emit the end-of-output boilerplate.
   */
! void
  ExplainEndOutput(ExplainState *es)
  {
      switch (es->format)
Index: src/include/commands/explain.h
===================================================================
RCS file: /cvsroot/pgsql/src/include/commands/explain.h,v
retrieving revision 1.41
diff -c -r1.41 explain.h
*** src/include/commands/explain.h    10 Aug 2009 05:46:50 -0000    1.41
--- src/include/commands/explain.h    17 Aug 2009 21:19:09 -0000
***************
*** 54,59 ****
--- 54,63 ----

  extern void ExplainInitState(ExplainState *es);

+ extern void ExplainBeginOutput(ExplainState *es);
+
+ extern void ExplainEndOutput(ExplainState *es);
+
  extern TupleDesc ExplainResultDesc(ExplainStmt *stmt);

  extern void ExplainOneUtility(Node *utilityStmt, ExplainState *es,