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postgres_fdw: More preliminary refactoring for upcoming join pushdown.

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The code that generates a complete SQL query for a given foreign relation
was repeated in two places, and they didn't quite agree: the EXPLAIN case
left out the locking clause.  Centralize the code so we get the same
behavior everywhere, and adjust calling conventions and which functions
are static vs. extern accordingly .  Centralize the code so we get the same
behavior everywhere, and adjust calling conventions and which functions
are static vs. extern accordingly.

Ashutosh Bapat, reviewed and slightly adjusted by me.
This commit is contained in:
Robert Haas
2016-01-30 10:32:38 -05:00
parent 2251179e6a
commit cc592c48c5
3 changed files with 93 additions and 90 deletions
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38
contrib/postgres_fdw/postgres_fdw.c
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@ -1003,19 +1003,9 @@ postgresGetForeignPlan(PlannerInfo *root,
* expressions to be sent as parameters.
*/
initStringInfo(&sql);
deparseSelectSql(&sql, root, baserel, fpinfo->attrs_used,
&retrieved_attrs);
if (remote_conds)
appendWhereClause(&sql, root, baserel, remote_conds,
true, &params_list);
/* Add ORDER BY clause if we found any useful pathkeys */
if (best_path->path.pathkeys)
appendOrderByClause(&sql, root, baserel, best_path->path.pathkeys);
/* Add any necessary FOR UPDATE/SHARE. */
deparseLockingClause(&sql, root, baserel);
deparseSelectStmtForRel(&sql, root, baserel, remote_conds,
best_path->path.pathkeys, &retrieved_attrs,
&params_list);
/*
* Build the fdw_private list that will be available to the executor.
* Items in the list must match enum FdwScanPrivateIndex, above.
@ -1909,6 +1899,7 @@ estimate_path_cost_size(PlannerInfo *root,
PGconn *conn;
Selectivity local_sel;
QualCost local_cost;
List *remote_conds;
/*
* join_conds might contain both clauses that are safe to send across,
@ -1917,6 +1908,14 @@ estimate_path_cost_size(PlannerInfo *root,
classifyConditions(root, baserel, join_conds,
&remote_join_conds, &local_join_conds);
/*
* The complete list of remote conditions includes everything from
* baserestrictinfo plus any extra join_conds relevant to this
* particular path.
*/
remote_conds = list_concat(list_copy(remote_join_conds),
fpinfo->remote_conds);
/*
* Construct EXPLAIN query including the desired SELECT, FROM, and
* WHERE clauses. Params and other-relation Vars are replaced by
@ -1924,17 +1923,8 @@ estimate_path_cost_size(PlannerInfo *root,
*/
initStringInfo(&sql);
appendStringInfoString(&sql, "EXPLAIN ");
deparseSelectSql(&sql, root, baserel, fpinfo->attrs_used,
&retrieved_attrs);
if (fpinfo->remote_conds)
appendWhereClause(&sql, root, baserel, fpinfo->remote_conds,
true, NULL);
if (remote_join_conds)
appendWhereClause(&sql, root, baserel, remote_join_conds,
(fpinfo->remote_conds == NIL), NULL);
if (pathkeys)
appendOrderByClause(&sql, root, baserel, pathkeys);
deparseSelectStmtForRel(&sql, root, baserel, remote_conds, pathkeys,
&retrieved_attrs, NULL);
/* Get the remote estimate */
conn = GetConnection(fpinfo->user, false);