Assert("vacrel->eager_scan_remaining_successes > 0")

Hi,

I hit the assertion failure in the subject line with the following script:

create table t (a int) with (autovacuum_enabled = off);
insert into t select generate_series(1, 1_000_000);
vacuum t;
insert into t select generate_series(1, 1_000_000);
set vacuum_freeze_min_age to 0;
vacuum t;

When the success count reaches to 0, we disable the eager scan by
resetting related fields as follows:

/*
 * If we hit our success cap, permanently disable eager
 * scanning by setting the other eager scan management
 * fields to their disabled values.
 */
vacrel->eager_scan_remaining_fails = 0;
vacrel->next_eager_scan_region_start = InvalidBlockNumber;
vacrel->eager_scan_max_fails_per_region = 0;

However, there is a possibility that we have already eagerly scanned
another page and returned it to the read stream before we freeze the
eagerly-scanned page and disable the eager scan. In this case, the
next block that we retrieved from the read stream could also be an
eagerly-scanned page.

Regards,

-- 
Masahiko Sawada
Amazon Web Services: https://aws.amazon.com