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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2019-01-25 17:09:45 -0500 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2019-01-25 17:09:45 -0500 |
| commit | 18c0da88a5d9da566c3bfac444366b73bd0b57da (patch) | |
| tree | 9ee280a42d3aa696c896eb3b82c7818578362ff6 /src/backend/nodes | |
| parent | ff750ce2d82979e9588c629955e161a9379b05f3 (diff) | |
| download | postgresql-18c0da88a5d9da566c3bfac444366b73bd0b57da.tar.gz postgresql-18c0da88a5d9da566c3bfac444366b73bd0b57da.zip | |
Split QTW_EXAMINE_RTES flag into QTW_EXAMINE_RTES_BEFORE/_AFTER.
This change allows callers of query_tree_walker() to choose whether
to visit an RTE before or after visiting the contents of the RTE
(i.e., prefix or postfix tree order). All existing users of
QTW_EXAMINE_RTES want the QTW_EXAMINE_RTES_BEFORE behavior, but
an upcoming patch will want QTW_EXAMINE_RTES_AFTER, and it seems
like a potentially useful change on its own.
Andreas Karlsson (extracted from CTE inlining patch)
Discussion: https://postgr.es/m/8810.1542402910@sss.pgh.pa.us
Diffstat (limited to 'src/backend/nodes')
| -rw-r--r-- | src/backend/nodes/nodeFuncs.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/src/backend/nodes/nodeFuncs.c b/src/backend/nodes/nodeFuncs.c index 19b65f681d1..a806d51edcd 100644 --- a/src/backend/nodes/nodeFuncs.c +++ b/src/backend/nodes/nodeFuncs.c @@ -2255,7 +2255,7 @@ expression_tree_walker(Node *node, * Some callers want to suppress visitation of certain items in the sub-Query, * typically because they need to process them specially, or don't actually * want to recurse into subqueries. This is supported by the flags argument, - * which is the bitwise OR of flag values to suppress visitation of + * which is the bitwise OR of flag values to add or suppress visitation of * indicated items. (More flag bits may be added as needed.) */ bool @@ -2314,8 +2314,12 @@ range_table_walker(List *rtable, { RangeTblEntry *rte = (RangeTblEntry *) lfirst(rt); - /* For historical reasons, visiting RTEs is not the default */ - if (flags & QTW_EXAMINE_RTES) + /* + * Walkers might need to examine the RTE node itself either before or + * after visiting its contents (or, conceivably, both). Note that if + * you specify neither flag, the walker won't visit the RTE at all. + */ + if (flags & QTW_EXAMINE_RTES_BEFORE) if (walker(rte, context)) return true; @@ -2355,6 +2359,10 @@ range_table_walker(List *rtable, if (walker(rte->securityQuals, context)) return true; + + if (flags & QTW_EXAMINE_RTES_AFTER) + if (walker(rte, context)) + return true; } return false; } |