Re: Force re-compression with lz4

2021-10-19 Thread Mladen Gogala
On 10/18/21 11:01, Adrian Klaver wrote: ot sure how much this applies to the Postgres usage of lz4. As I understand it, this is only used internally for table compression. When using pg_dump compression gzip is used. Unless you pipe plain text output through some other program. This appli

Re: Force re-compression with lz4

2021-10-18 Thread Michael Paquier
On Mon, Oct 18, 2021 at 08:01:04AM -0700, Adrian Klaver wrote: > Not sure how much this applies to the Postgres usage of lz4. As I understand > it, this is only used internally for table compression. When using pg_dump > compression gzip is used. Unless you pipe plain text output through some > oth

Re: Force re-compression with lz4

2021-10-18 Thread Adrian Klaver
On 10/18/21 06:41, Mladen Gogala wrote: On 10/18/21 01:07, Michael Paquier wrote: CPU-speaking, LZ4 is*much*  faster than pglz when it comes to compression or decompression with its default options.  The compression ratio is comparable between both, still LZ4 compresses in average less than PGL

Re: Force re-compression with lz4

2021-10-18 Thread Mladen Gogala
On 10/18/21 01:07, Michael Paquier wrote: CPU-speaking, LZ4 is*much* faster than pglz when it comes to compression or decompression with its default options. The compression ratio is comparable between both, still LZ4 compresses in average less than PGLZ. -- Michael LZ4 works much better wi

Re: Force re-compression with lz4

2021-10-18 Thread Magnus Hagander
On Mon, Oct 18, 2021 at 7:18 AM Michael Paquier wrote: > On Sun, Oct 17, 2021 at 10:13:48PM +0300, Florents Tselai wrote: > > I did look into VACUUM(full) for it’s PROCESS_TOAST option which > > makes sense, but the thing is I already had a cron-ed VACUUM (full) > > which I ended up disabling a w

Re: Force re-compression with lz4

2021-10-18 Thread Michael Paquier
On Mon, Oct 18, 2021 at 09:57:11AM +0300, Florents Tselai wrote: > Oh, that’s good to know then. So besides ALTER COMPRESSION for > future inserts there’s not much one can do for pre-existing values The posting style of the mailing list is to not top-post, so if you could avoid breaking the logic

Re: Force re-compression with lz4

2021-10-17 Thread Florents Tselai
Oh, that’s good to know then. So besides ALTER COMPRESSION for future inserts there’s not much one can do for pre-existing values I think it makes sense to update/ add more info to the docs on this as well, since other people in the thread expected this to work that way too. Maybe at some point,

Re: Force re-compression with lz4

2021-10-17 Thread Francisco Olarte
On Sun, 17 Oct 2021 at 21:04, Florents Tselai wrote: > Yes, That COPY-delete-COPY sequence is what I ended up doing. > Unfortunately can’t use ranges as the PK its a text string. Unless you have a really weird PK and have trouble calculating bounds, text strings are sortable and fine to use as ra

Re: Force re-compression with lz4

2021-10-17 Thread Michael Paquier
On Sun, Oct 17, 2021 at 10:13:48PM +0300, Florents Tselai wrote: > I did look into VACUUM(full) for it’s PROCESS_TOAST option which > makes sense, but the thing is I already had a cron-ed VACUUM (full) > which I ended up disabling a while back; exactly because of the > double-space requirement. Pl

Re: Force re-compression with lz4

2021-10-17 Thread Michael Paquier
On Sun, Oct 17, 2021 at 10:33:52PM +0200, Daniel Verite wrote: > However lz4 appears to be much faster to compress than pglz, so its > benefit is clear in terms of CPU usage for future insertions. CPU-speaking, LZ4 is *much* faster than pglz when it comes to compression or decompression with its d

Re: Force re-compression with lz4

2021-10-17 Thread Daniel Verite
Florents Tselai wrote: > I have a table storing mostly text data (40M+ rows) that has > pg_total_relation_size ~670GB. > I’ve just upgraded to postgres 14 and I’m now eager to try the new LZ4 > compression. You could start experimenting with data samples rather than the full contents. FW

Re: Force re-compression with lz4

2021-10-17 Thread Florents Tselai
I did look into VACUUM(full) for it’s PROCESS_TOAST option which makes sense, but the thing is I already had a cron-ed VACUUM (full) which I ended up disabling a while back; exactly because of the double-space requirement. The DB has already a 1TB size and occupying another 600MB would require so

Re: Force re-compression with lz4

2021-10-17 Thread Florents Tselai
Yes, That COPY-delete-COPY sequence is what I ended up doing. Unfortunately can’t use ranges as the PK its a text string. > On 17 Oct 2021, at 7:36 PM, Ron wrote: > > On 10/17/21 10:12 AM, Florents Tselai wrote: >> Hello, >> >> I have a table storing mostly text data (40M+ rows) that has >> pg

Re: Force re-compression with lz4

2021-10-17 Thread Adrian Klaver
On 10/17/21 10:17, Magnus Hagander wrote: On Sun, Oct 17, 2021 at 5:12 PM Florents Tselai mailto:florents.tse...@gmail.com>> wrote: Is there a smarter way to do this ? It should be enough to VACUUM FULL the table. (but it has to be VACUUM FULL, not a regular vacuum). Or CLUSTER. With

Re: Force re-compression with lz4

2021-10-17 Thread Magnus Hagander
On Sun, Oct 17, 2021 at 5:12 PM Florents Tselai wrote: > Hello, > > I have a table storing mostly text data (40M+ rows) that has > pg_total_relation_size ~670GB. > I’ve just upgraded to postgres 14 and I’m now eager to try the new LZ4 > compression. > > I’ve altered the column to use the new lz4

Re: Force re-compression with lz4

2021-10-17 Thread Ron
On 10/17/21 11:36 AM, Ron wrote: On 10/17/21 10:12 AM, Florents Tselai wrote: Hello, I have a table storing mostly text data (40M+ rows) that has pg_total_relation_size ~670GB. I’ve just upgraded to postgres 14 and I’m now eager to try the new LZ4 compression. I’ve altered the column to use

Re: Force re-compression with lz4

2021-10-17 Thread Ron
On 10/17/21 10:12 AM, Florents Tselai wrote: Hello, I have a table storing mostly text data (40M+ rows) that has pg_total_relation_size ~670GB. I’ve just upgraded to postgres 14 and I’m now eager to try the new LZ4 compression. I’ve altered the column to use the new lz4 compression, but that