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Don't use abbreviated keys for the final merge pass.

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When we write tuples out to disk and read them back in, the abbreviated
keys become non-abbreviated, because the readtup routines don't know
anything about abbreviation.  But without this fix, the rest of the
code still thinks the abbreviation-aware compartor should be used,
so chaos ensues.

Report by Andrew Gierth; patch by Peter Geoghegan.
This commit is contained in:
Robert Haas
2015-01-23 11:58:31 -05:00
parent 6a3c6ba0ba
commit 5cefbf5a6c
1 changed files with 16 additions and 0 deletions
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16
src/backend/utils/sort/tuplesort.c
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@ -2172,6 +2172,22 @@ mergeruns(Tuplesortstate *state)
return; return;
} }
if (state->sortKeys->abbrev_converter)
{
/*
* If there are multiple runs to be merged, when we go to read back
* tuples from disk, abbreviated keys will not have been stored, and we
* don't care to regenerate them. Disable abbreviation from this point
* on.
*/
state->sortKeys->abbrev_converter = NULL;
state->sortKeys->comparator = state->sortKeys->abbrev_full_comparator;
/* Not strictly necessary, but be tidy */
state->sortKeys->abbrev_abort = NULL;
state->sortKeys->abbrev_full_comparator = NULL;
}
/* End of step D2: rewind all output tapes to prepare for merging */ /* End of step D2: rewind all output tapes to prepare for merging */
for (tapenum = 0; tapenum < state->tapeRange; tapenum++) for (tapenum = 0; tapenum < state->tapeRange; tapenum++)
LogicalTapeRewind(state->tapeset, tapenum, false); LogicalTapeRewind(state->tapeset, tapenum, false);