diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/commands/analyze.c | 21 |
1 files changed, 18 insertions, 3 deletions
diff --git a/src/backend/commands/analyze.c b/src/backend/commands/analyze.c index 9498546f8c3..9581c2c0287 100644 --- a/src/backend/commands/analyze.c +++ b/src/backend/commands/analyze.c @@ -1124,20 +1124,35 @@ acquire_sample_rows(Relation onerel, int elevel, case HEAPTUPLE_DELETE_IN_PROGRESS: /* - * We count delete-in-progress rows as still live, using - * the same reasoning given above; but we don't bother to - * include them in the sample. + * We count and sample delete-in-progress rows the same as + * live ones, so that the stats counters come out right if + * the deleting transaction commits after us, per the same + * reasoning given above. * * If the delete was done by our own transaction, however, * we must count the row as dead to make * pgstat_report_analyze's stats adjustments come out * right. (Note: this works out properly when the row was * both inserted and deleted in our xact.) + * + * The net effect of these choices is that we act as + * though an IN_PROGRESS transaction hasn't happened yet, + * except if it is our own transaction, which we assume + * has happened. + * + * This approach ensures that we behave sanely if we see + * both the pre-image and post-image rows for a row being + * updated by a concurrent transaction: we will sample the + * pre-image but not the post-image. We also get sane + * results if the concurrent transaction never commits. */ if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetUpdateXid(targtuple.t_data))) deadrows += 1; else + { + sample_it = true; liverows += 1; + } break; default: |