diff options
Diffstat (limited to 'src/backend/commands/explain.c')
| -rw-r--r-- | src/backend/commands/explain.c | 14 |
1 files changed, 4 insertions, 10 deletions
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c index 9a60865d191..e81b9900925 100644 --- a/src/backend/commands/explain.c +++ b/src/backend/commands/explain.c @@ -256,14 +256,8 @@ ExplainQuery(ParseState *pstate, ExplainStmt *stmt, * rewriter. We do not do AcquireRewriteLocks: we assume the query either * came straight from the parser, or suitable locks were acquired by * plancache.c. - * - * Because the rewriter and planner tend to scribble on the input, we make - * a preliminary copy of the source querytree. This prevents problems in - * the case that the EXPLAIN is in a portal or plpgsql function and is - * executed repeatedly. (See also the same hack in DECLARE CURSOR and - * PREPARE.) XXX FIXME someday. */ - rewritten = QueryRewrite(castNode(Query, copyObject(stmt->query))); + rewritten = QueryRewrite(castNode(Query, stmt->query)); /* emit opening boilerplate */ ExplainBeginOutput(es); @@ -427,7 +421,8 @@ ExplainOneQuery(Query *query, int cursorOptions, * "into" is NULL unless we are explaining the contents of a CreateTableAsStmt. * * This is exported because it's called back from prepare.c in the - * EXPLAIN EXECUTE case. + * EXPLAIN EXECUTE case. In that case, we'll be dealing with a statement + * that's in the plan cache, so we have to ensure we don't modify it. */ void ExplainOneUtility(Node *utilityStmt, IntoClause *into, ExplainState *es, @@ -441,8 +436,7 @@ ExplainOneUtility(Node *utilityStmt, IntoClause *into, ExplainState *es, { /* * We have to rewrite the contained SELECT and then pass it back to - * ExplainOneQuery. It's probably not really necessary to copy the - * contained parsetree another time, but let's be safe. + * ExplainOneQuery. Copy to be safe in the EXPLAIN EXECUTE case. */ CreateTableAsStmt *ctas = (CreateTableAsStmt *) utilityStmt; List *rewritten; |