diff options
Diffstat (limited to 'contrib/amcheck')
| -rw-r--r-- | contrib/amcheck/verify_heapam.c | 33 |
1 files changed, 28 insertions, 5 deletions
diff --git a/contrib/amcheck/verify_heapam.c b/contrib/amcheck/verify_heapam.c index 33c5b338959..94ddccd23a8 100644 --- a/contrib/amcheck/verify_heapam.c +++ b/contrib/amcheck/verify_heapam.c @@ -1574,17 +1574,40 @@ check_tuple(HeapCheckContext *ctx) static FullTransactionId FullTransactionIdFromXidAndCtx(TransactionId xid, const HeapCheckContext *ctx) { - uint32 epoch; + uint64 nextfxid_i; + int32 diff; + FullTransactionId fxid; Assert(TransactionIdIsNormal(ctx->next_xid)); Assert(FullTransactionIdIsNormal(ctx->next_fxid)); + Assert(XidFromFullTransactionId(ctx->next_fxid) == ctx->next_xid); if (!TransactionIdIsNormal(xid)) return FullTransactionIdFromEpochAndXid(0, xid); - epoch = EpochFromFullTransactionId(ctx->next_fxid); - if (xid > ctx->next_xid) - epoch--; - return FullTransactionIdFromEpochAndXid(epoch, xid); + + nextfxid_i = U64FromFullTransactionId(ctx->next_fxid); + + /* compute the 32bit modulo difference */ + diff = (int32) (ctx->next_xid - xid); + + /* + * In cases of corruption we might see a 32bit xid that is before epoch + * 0. We can't represent that as a 64bit xid, due to 64bit xids being + * unsigned integers, without the modulo arithmetic of 32bit xid. There's + * no really nice way to deal with that, but it works ok enough to use + * FirstNormalFullTransactionId in that case, as a freshly initdb'd + * cluster already has a newer horizon. + */ + if (diff > 0 && (nextfxid_i - FirstNormalTransactionId) < (int64) diff) + { + Assert(EpochFromFullTransactionId(ctx->next_fxid) == 0); + fxid = FirstNormalFullTransactionId; + } + else + fxid = FullTransactionIdFromU64(nextfxid_i - diff); + + Assert(FullTransactionIdIsNormal(fxid)); + return fxid; } /* |