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Reinstate HEAP_XMAX_LOCK_ONLY|HEAP_KEYS_UPDATED as allowed

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Commit 866e24d47d added an assert that HEAP_XMAX_LOCK_ONLY and
HEAP_KEYS_UPDATED cannot appear together, on the faulty assumption that
the latter necessarily referred to an update and not a tuple lock; but
that's wrong, because SELECT FOR UPDATE can use precisely that
combination, as evidenced by the amcheck test case added here.

Remove the Assert(), and also patch amcheck's verify_heapam.c to not
complain if the combination is found.  Also, out of overabundance of
caution, update (across all branches) README.tuplock to be more explicit
about this.

Author: Julien Rouhaud <rjuju123@gmail.com>
Reviewed-by: Mahendra Singh Thalor <mahi6run@gmail.com>
Reviewed-by: Dilip Kumar <dilipbalaut@gmail.com>
Discussion: https://postgr.es/m/20210124061758.GA11756@nol
This commit is contained in:
Alvaro Herrera
2021-02-23 17:30:21 -03:00
parent 3db05e76f9
commit 8deb6b38dc
4 changed files with 20 additions and 16 deletions
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7
contrib/amcheck/verify_heapam.c
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@ -608,13 +608,6 @@ check_tuple_header_and_visibilty(HeapTupleHeader tuphdr, HeapCheckContext *ctx)
ctx->tuphdr->t_hoff, ctx->lp_len));
header_garbled = true;
}
if ((ctx->tuphdr->t_infomask & HEAP_XMAX_LOCK_ONLY) &&
(ctx->tuphdr->t_infomask2 & HEAP_KEYS_UPDATED))
{
report_corruption(ctx,
pstrdup("tuple is marked as only locked, but also claims key columns were updated"));
header_garbled = true;
}
if ((ctx->tuphdr->t_infomask & HEAP_XMAX_COMMITTED) &&
(ctx->tuphdr->t_infomask & HEAP_XMAX_IS_MULTI))