Horton

Re: Make query cancellation keys longer

Jelte Fennema-Nio <postgres@jeltef.nl>

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From: Jelte Fennema-Nio <postgres@jeltef.nl>
To: Heikki Linnakangas <hlinnaka@iki.fi>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2024-03-03T17:27:56Z
Lists: pgsql-hackers 
On Sun, 3 Mar 2024 at 15:27, Jelte Fennema-Nio <postgres@jeltef.nl> wrote:
> + case EOF:
> + /* We'll come back when there is more data */
> + return PGRES_POLLING_READING;
>
> Nice catch, I'll go steal this for my patchset which adds all the
> necessary changes to be able to do a protocol bump[1].

Actually, it turns out your change to return PGRES_POLLING_READING on
EOF is incorrect (afaict). A little bit above there is this code
comment above a check to see if the whole body was received:

 * Can't process if message body isn't all here yet.
 *
 * After this check passes, any further EOF during parsing
 * implies that the server sent a bad/truncated message.
 * Reading more bytes won't help in that case, so don't return
 * PGRES_POLLING_READING after this point.

So I'll leave my patchset as is.

Commits

  1. Add timingsafe_bcmp(), for constant-time memory comparison

  2. Add missing declarations to pg_config.h.in

  3. docs: Add a new section and a table listing protocol versions

  4. Make cancel request keys longer

  5. libpq: Add min/max_protocol_version connection options

  6. libpq: Handle NegotiateProtocolVersion message differently

  7. docs: Update phrase on message lengths in the protocol

  8. libpq: Trace all NegotiateProtocolVersion fields

  9. libpq: Add PQfullProtocolVersion to exports.txt

  10. Move cancel key generation to after forking the backend