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Do parse analysis of an EXPLAIN's contained statement during the normal
parse analysis phase, rather than at execution time. This makes parameter handling work the same as it does in ordinary plannable queries, and in particular fixes the incompatibility that Pavel pointed out with plpgsql's new handling of variable references. plancache.c gets a little bit grottier, but the alternatives seem worse.
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9 files changed

+141
-128
lines changed

9 files changed

+141
-128
lines changed

‎src/backend/commands/explain.c

Lines changed: 9 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1994-5, Regents of the University of California
88
*
99
* IDENTIFICATION
10-
* $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.198 2010/01/02 16:57:37 momjian Exp $
10+
* $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.199 2010/01/15 22:36:29 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -158,19 +158,19 @@ ExplainQuery(ExplainStmt *stmt, const char *queryString,
158158
errmsg("EXPLAIN option BUFFERS requires ANALYZE")));
159159

160160
/*
161-
* Run parse analysis and rewrite. Note this also acquires sufficient
162-
* locks on the source table(s).
161+
* Parse analysis was done already, but we still have to run the rule
162+
* rewriter. We do not do AcquireRewriteLocks: we assume the query
163+
* either came straight from the parser, or suitable locks were
164+
* acquired by plancache.c.
163165
*
164-
* Because the parser and planner tend to scribble on their input, we make
166+
* Because the rewriter and planner tend to scribble on the input, we make
165167
* a preliminary copy of the source querytree. This prevents problems in
166168
* the case that the EXPLAIN is in a portal or plpgsql function and is
167169
* executed repeatedly. (See also the same hack in DECLARE CURSOR and
168170
* PREPARE.) XXX FIXME someday.
169171
*/
170-
rewritten = pg_analyze_and_rewrite_params((Node *) copyObject(stmt->query),
171-
queryString,
172-
(ParserSetupHook) setupParserWithParamList,
173-
params);
172+
Assert(IsA(stmt->query, Query));
173+
rewritten = QueryRewrite((Query *) copyObject(stmt->query));
174174

175175
/* emit opening boilerplate */
176176
ExplainBeginOutput(&es);
@@ -248,6 +248,7 @@ ExplainResultDesc(ExplainStmt *stmt)
248248
char *p = defGetString(opt);
249249

250250
xml = (strcmp(p, "xml") == 0);
251+
/* don't "break", as ExplainQuery will use the last value */
251252
}
252253
}
253254

‎src/backend/nodes/params.c

Lines changed: 1 addition & 45 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/nodes/params.c,v 1.13 2010/01/02 16:57:46 momjian Exp $
11+
* $PostgreSQL: pgsql/src/backend/nodes/params.c,v 1.14 2010/01/15 22:36:31 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -75,47 +75,3 @@ copyParamList(ParamListInfo from)
7575

7676
return retval;
7777
}
78-
79-
/*
80-
* Set up the parser to treat the given list of run-time parameters
81-
* as available external parameters during parsing of a new query.
82-
*
83-
* Note that the parser doesn't actually care about the *values* of the given
84-
* parameters, only about their *types*. Also, the code that originally
85-
* provided the ParamListInfo may have provided a setupHook, which should
86-
* override applying parse_fixed_parameters().
87-
*/
88-
void
89-
setupParserWithParamList(struct ParseState *pstate,
90-
ParamListInfo params)
91-
{
92-
if (params == NULL) /* no params, nothing to do */
93-
return;
94-
95-
/* If there is a parserSetup hook, it gets to do this */
96-
if (params->parserSetup != NULL)
97-
{
98-
(*params->parserSetup) (pstate, params->parserSetupArg);
99-
return;
100-
}
101-
102-
/* Else, treat any available parameters as being of fixed type */
103-
if (params->numParams > 0)
104-
{
105-
Oid *ptypes;
106-
int i;
107-
108-
ptypes = (Oid *) palloc(params->numParams * sizeof(Oid));
109-
for (i = 0; i < params->numParams; i++)
110-
{
111-
ParamExternData *prm = &params->params[i];
112-
113-
/* give hook a chance in case parameter is dynamic */
114-
if (!OidIsValid(prm->ptype) && params->paramFetch != NULL)
115-
(*params->paramFetch) (params, i+1);
116-
117-
ptypes[i] = prm->ptype;
118-
}
119-
parse_fixed_parameters(pstate, ptypes, params->numParams);
120-
}
121-
}

‎src/backend/optimizer/plan/setrefs.c

Lines changed: 19 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -9,7 +9,7 @@
99
*
1010
*
1111
* IDENTIFICATION
12-
* $PostgreSQL: pgsql/src/backend/optimizer/plan/setrefs.c,v 1.156 2010/01/02 16:57:47 momjian Exp $
12+
* $PostgreSQL: pgsql/src/backend/optimizer/plan/setrefs.c,v 1.157 2010/01/15 22:36:32 tgl Exp $
1313
*
1414
*-------------------------------------------------------------------------
1515
*/
@@ -1905,14 +1905,15 @@ record_plan_function_dependency(PlannerGlobal *glob, Oid funcid)
19051905

19061906
/*
19071907
* extract_query_dependencies
1908-
* Given a list of not-yet-planned queries (i.e. Query nodes),
1909-
* extract their dependencies just as set_plan_references would do.
1908+
* Given a not-yet-planned query or queries (i.e. a Query node or list
1909+
* of Query nodes), extract dependencies just as set_plan_references
1910+
* would do.
19101911
*
19111912
* This is needed by plancache.c to handle invalidation of cached unplanned
19121913
* queries.
19131914
*/
19141915
void
1915-
extract_query_dependencies(List *queries,
1916+
extract_query_dependencies(Node *query,
19161917
List **relationOids,
19171918
List **invalItems)
19181919
{
@@ -1924,7 +1925,7 @@ extract_query_dependencies(List *queries,
19241925
glob.relationOids = NIL;
19251926
glob.invalItems = NIL;
19261927

1927-
(void) extract_query_dependencies_walker((Node *) queries, &glob);
1928+
(void) extract_query_dependencies_walker(query, &glob);
19281929

19291930
*relationOids = glob.relationOids;
19301931
*invalItems = glob.invalItems;
@@ -1943,6 +1944,19 @@ extract_query_dependencies_walker(Node *node, PlannerGlobal *context)
19431944
Query *query = (Query *) node;
19441945
ListCell *lc;
19451946

1947+
if (query->commandType == CMD_UTILITY)
1948+
{
1949+
/* Ignore utility statements, except EXPLAIN */
1950+
if (IsA(query->utilityStmt, ExplainStmt))
1951+
{
1952+
query = (Query *) ((ExplainStmt *) query->utilityStmt)->query;
1953+
Assert(IsA(query, Query));
1954+
Assert(query->commandType != CMD_UTILITY);
1955+
}
1956+
else
1957+
return false;
1958+
}
1959+
19461960
/* Collect relation OIDs in this Query's rtable */
19471961
foreach(lc, query->rtable)
19481962
{

‎src/backend/parser/analyze.c

Lines changed: 11 additions & 23 deletions
Original file line numberDiff line numberDiff line change
@@ -17,7 +17,7 @@
1717
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
1818
* Portions Copyright (c) 1994, Regents of the University of California
1919
*
20-
* $PostgreSQL: pgsql/src/backend/parser/analyze.c,v 1.399 2010/01/02 16:57:48 momjian Exp $
20+
* $PostgreSQL: pgsql/src/backend/parser/analyze.c,v 1.400 2010/01/15 22:36:33 tgl Exp $
2121
*
2222
*-------------------------------------------------------------------------
2323
*/
@@ -257,16 +257,12 @@ analyze_requires_snapshot(Node *parseTree)
257257
break;
258258

259259
case T_ExplainStmt:
260-
261-
/*
262-
* We only need a snapshot in varparams case, but it doesn't seem
263-
* worth complicating this function's API to distinguish that.
264-
*/
260+
/* yes, because we must analyze the contained statement */
265261
result = true;
266262
break;
267263

268264
default:
269-
/* utility statements don't have any active parse analysis */
265+
/* other utility statements don't have any real parse analysis */
270266
result = false;
271267
break;
272268
}
@@ -1993,29 +1989,21 @@ transformDeclareCursorStmt(ParseState *pstate, DeclareCursorStmt *stmt)
19931989
* transformExplainStmt -
19941990
* transform an EXPLAIN Statement
19951991
*
1996-
* EXPLAIN is just like other utility statements in that we emit it as a
1997-
* CMD_UTILITY Query node with no transformation of the raw parse tree.
1998-
* However, if p_coerce_param_hook is set, it could be that the client is
1999-
* expecting us to resolve parameter types in something like
2000-
* EXPLAIN SELECT * FROM tab WHERE col = $1
2001-
* To deal with such cases, we run parse analysis and throw away the result;
2002-
* this is a bit grotty but not worth contorting the rest of the system for.
2003-
* (The approach we use for DECLARE CURSOR won't work because the statement
2004-
* being explained isn't necessarily a SELECT, and in particular might rewrite
2005-
* to multiple parsetrees.)
1992+
* EXPLAIN is like other utility statements in that we emit it as a
1993+
* CMD_UTILITY Query node; however, we must first transform the contained
1994+
* query. We used to postpone that until execution, but it's really necessary
1995+
* to do it during the normal parse analysis phase to ensure that side effects
1996+
* of parser hooks happen at the expected time.
20061997
*/
20071998
static Query *
20081999
transformExplainStmt(ParseState *pstate, ExplainStmt *stmt)
20092000
{
20102001
Query *result;
20112002

2012-
if (pstate->p_coerce_param_hook != NULL)
2013-
{
2014-
/* Since parse analysis scribbles on its input, copy the tree first! */
2015-
(void) transformStmt(pstate, copyObject(stmt->query));
2016-
}
2003+
/* transform contained query */
2004+
stmt->query = (Node *) transformStmt(pstate, stmt->query);
20172005

2018-
/* Now return the untransformed command as a utility Query */
2006+
/* represent the command as a utility Query */
20192007
result = makeNode(Query);
20202008
result->commandType = CMD_UTILITY;
20212009
result->utilityStmt = (Node *) stmt;

‎src/backend/tcop/utility.c

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -10,7 +10,7 @@
1010
*
1111
*
1212
* IDENTIFICATION
13-
* $PostgreSQL: pgsql/src/backend/tcop/utility.c,v 1.328 2010/01/06 03:04:01 momjian Exp $
13+
* $PostgreSQL: pgsql/src/backend/tcop/utility.c,v 1.329 2010/01/15 22:36:34 tgl Exp $
1414
*
1515
*-------------------------------------------------------------------------
1616
*/
@@ -2438,6 +2438,7 @@ GetCommandLogLevel(Node *parsetree)
24382438

24392439
if (strcmp(opt->defname, "analyze") == 0)
24402440
analyze = defGetBoolean(opt);
2441+
/* don't "break", as explain.c will use the last value */
24412442
}
24422443
if (analyze)
24432444
return GetCommandLogLevel(stmt->query);

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