Horton

Re: Minimal logical decoding on standbys

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Robert Haas <robertmhaas@gmail.com>
Cc: "Drouvot, Bertrand" <bertranddrouvot.pg@gmail.com>, Alvaro Herrera <alvherre@2ndquadrant.com>, Ibrar Ahmed <ibrar.ahmad@gmail.com>, Amit Khandekar <amitdkhan.pg@gmail.com>, fabriziomello@gmail.com, tushar <tushar.ahuja@enterprisedb.com>, Rahila Syed <rahila.syed@2ndquadrant.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2022-12-14T17:35:52Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Reduce the log level in 035_standby_logical_decoding.pl.

  2. 035_standby_logical_decoding: Add missing waits for replication

  3. For cascading replication, wake physical and logical walsenders separately

  4. Handle logical slot conflicts on standby

  5. Support invalidating replication slots due to horizon and wal_level

  6. Prevent use of invalidated logical slot in CreateDecodingContext()

  7. Replace replication slot's invalidated_at LSN with an enum

  8. Pass down table relation into more index relation functions

  9. Assert only valid flag bits are passed to visibilitymap_set()

  10. Remove unused _bt_delitems_delete() argument.

  11. Add xl_btree_delete optimization.

Hi,

On 2022-12-14 10:55:31 -0500, Robert Haas wrote:
> I read through 0001 again and I noticed this:
> 
>  typedef struct xl_heap_prune
>  {
>      TransactionId snapshotConflictHorizon;
>      uint16      nredirected;
>      uint16      ndead;
> +    bool        onCatalogAccessibleInLogicalDecoding;
>      /* OFFSET NUMBERS are in the block reference 0 */
>  } xl_heap_prune;
> 
> I think this is unsafe on alignment-picky machines. I think it will
> cause the offset numbers to be aligned at an odd address.
> heap_xlog_prune() doesn't copy the data into aligned memory, so I
> think this will result in a misaligned pointer being passed down to
> heap_page_prune_execute.

I think the offset numbers are stored separately from the record, even
though it doesn't quite look like that in the above due to the way the
'OFFSET NUMBERS' is embedded in the struct. As they're stored with the
block reference 0, the added boolean shouldn't make a difference
alignment wise?

Or am I misunderstanding your point?

Greetings,

Andres Freund