Re: ERROR: invalid memory alloc request size 18446744073709551613

Hello all,

I’ve got successfully isolate and delete the corrupted rows at the table, but what would caused that? How to prevent it?

Thanks in advance,
Flaris.

Flaris R. Feller
48-999811781
flaris(dot)feller(at)gmail(dot)com
http://linkedin.com/in/flarisfeller

> Em 22 de jun de 2020, à(s) 13:54, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> escreveu:
>
> Flaris Feller <flaris(dot)feller(at)gmail(dot)com> writes:
>>> Em seg., 22 de jun. de 2020 às 12:33, Peter J. Holzer <hjp-pgsql(at)hjp(dot)at>
>>> escreveu:
>>> On 2020-06-22 11:13:33 -0300, Flaris Feller wrote:
>>>> When using Postgres 9.6.15 on "CentOS Linux release 7.5.1804 (Core)" on
>>>> Intel x86_64 I noticed "invalid memory alloc request size" error at PostgreSQL
>>>> logs.
>
>>> That's 2**64 - 3. So probably the size of some object is (erroneously)
>>> computed as -3 bytes.
>
> Yeah. I don't recall the bit-level details offhand, but this is an
> extremely common symptom of a corrupted length word in a variable-length
> field.
>
> The usual approach is to try to isolate which row or rows contains corrupt
> data and then delete it. I'm not aware of any tools for doing that
> automatically, but you can usually home in on a bad row by a process of
> binary search, eg testing how many rows you can fetch without seeing the
> error. Also "select * from mytab where ctid = '(m,n)'" is useful for
> probing individual rows, once you get close to the problem area.
>
> regards, tom lane