Making --error-on-invalid-index the default behavior

[zubeyr94]

Hello, currently the default behavior in pg_repack is to repack tables even if tables have invalid indexes on them. Users can force pg_repack to error when there are invalid indexes on tables before they are repacked by providing -error-on-invalid-index parameter on pg_repack 1.5.0 and later versions.

However, repacking tables with invalid indexes would cause the index to be corrupted, because repack will skip repacking the invalid index and old heap tuple id in the index now be pointing to incorrect tuples on the relation. As a safety feature it would make sense to make --error-on-invalid-index the default behavior and there could be an option like --warn-on-invalid-index or --no-error-on-invalid-index for users who want to keep the old behavior.

[MasahikoSawada]

However, repacking tables with invalid indexes would cause the index to be corrupted. As a safety feature it would make sense to make --error-on-invalid-index the default behavior

What do exactly mean by safety feature? It's right that invalid indexes could corrupted after repacking a table, but invalid indexes are not used unless they are reindexed.

[zubeyr94]

Postgres continues to update indexes if indisready set to true, even if index is invalid, ie indisvalid is false. On a corrupted index, checks made during index insertion could cause transactions to rollback, eg this check could fail. Until users realize this and drop/reindex the indexes they won't be able to unblock the transaction doing the insertion. Instead of taking the hit while running regular workload, it should be preferable to take the hit during maintenance work, ie while running pg_repack and make users aware that they need to reindex or drop before completing the repack.