diff options
Diffstat (limited to 'src/backend/commands/portalcmds.c')
| -rw-r--r-- | src/backend/commands/portalcmds.c | 28 |
1 files changed, 20 insertions, 8 deletions
diff --git a/src/backend/commands/portalcmds.c b/src/backend/commands/portalcmds.c index 1bd2bf39b15..a413e8beed9 100644 --- a/src/backend/commands/portalcmds.c +++ b/src/backend/commands/portalcmds.c @@ -382,6 +382,15 @@ PersistHoldablePortal(Portal portal) * can be processed. Otherwise, store only the not-yet-fetched rows. * (The latter is not only more efficient, but avoids semantic * problems if the query's output isn't stable.) + * + * In the no-scroll case, tuple indexes in the tuplestore will not + * match the cursor's nominal position (portalPos). Currently this + * causes no difficulty because we only navigate in the tuplestore by + * relative position, except for the tuplestore_skiptuples call below + * and the tuplestore_rescan call in DoPortalRewind, both of which are + * disabled for no-scroll cursors. But someday we might need to track + * the offset between the holdStore and the cursor's nominal position + * explicitly. */ if (portal->cursorOptions & CURSOR_OPT_SCROLL) { @@ -389,10 +398,6 @@ PersistHoldablePortal(Portal portal) } else { - /* Disallow moving backwards from here */ - portal->atStart = true; - portal->portalPos = 0; - /* * If we already reached end-of-query, set the direction to * NoMovement to avoid trying to fetch any tuples. (This check @@ -448,10 +453,17 @@ PersistHoldablePortal(Portal portal) { tuplestore_rescan(portal->holdStore); - if (!tuplestore_skiptuples(portal->holdStore, - portal->portalPos, - true)) - elog(ERROR, "unexpected end of tuple stream"); + /* + * In the no-scroll case, the start of the tuplestore is exactly + * where we want to be, so no repositioning is wanted. + */ + if (portal->cursorOptions & CURSOR_OPT_SCROLL) + { + if (!tuplestore_skiptuples(portal->holdStore, + portal->portalPos, + true)) + elog(ERROR, "unexpected end of tuple stream"); + } } } PG_CATCH(); |