Обсуждение: HOT readme missing documentation on summarizing index handling
Hi, With PG16's 19d8e230, we got rid of BRIN's blocking of HOT updates, but I just realized that we failed to update the README.HOT document with this new exception for summarizing indexes. Attached a patch that updates that document, detailing the related rationale. I'm not sure if such internal documentation is relevant for backpatching, but I also don't think it woudl hurt to have this included in the REL_16_STABLE branch. Kind regards, Matthias van de Meent Neon (https://neon.tech/)
Вложения
Yeah, README.HOT should have been updated, and I see no reason not to backpatch this to v16. Barring objections, I'll do that tomorrow. I have two suggesting regarding the README.HOT changes: 1) I'm not entirely sure it's very clear what "referential integrity of indexes across tuple updates" actually means. I'm afraid "referential integrity" may lead readers to think about foreign keys. Maybe it'd be better to explain this is about having index pointers to the new tuple version, etc. 2) Wouldn't it be good to make it a bit more explicit we now have three "levels" of HOT: (a) no indexes need update (b) update only summarizing indexes (c) update all indexes The original text was really about on/off, and I'm not quite sure the part about "exception" makes this very clear. regards -- Tomas Vondra EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
On Fri, 7 Jul 2023 at 00:14, Tomas Vondra <tomas.vondra@enterprisedb.com> wrote: > > Yeah, README.HOT should have been updated, and I see no reason not to > backpatch this to v16. Barring objections, I'll do that tomorrow. > > I have two suggesting regarding the README.HOT changes: > > 1) I'm not entirely sure it's very clear what "referential integrity of > indexes across tuple updates" actually means. I'm afraid "referential > integrity" may lead readers to think about foreign keys. Maybe it'd be > better to explain this is about having index pointers to the new tuple > version, etc. > > 2) Wouldn't it be good to make it a bit more explicit we now have three > "levels" of HOT: > > (a) no indexes need update > (b) update only summarizing indexes > (c) update all indexes > > The original text was really about on/off, and I'm not quite sure the > part about "exception" makes this very clear. Agreed on both points. Attached an updated version which incorporates your points. Kind regards, Matthias van de Meent Neon (https://neon.tech)
Вложения
On 7/7/23 18:34, Matthias van de Meent wrote: > On Fri, 7 Jul 2023 at 00:14, Tomas Vondra <tomas.vondra@enterprisedb.com> wrote: >> >> Yeah, README.HOT should have been updated, and I see no reason not to >> backpatch this to v16. Barring objections, I'll do that tomorrow. >> >> I have two suggesting regarding the README.HOT changes: >> >> 1) I'm not entirely sure it's very clear what "referential integrity of >> indexes across tuple updates" actually means. I'm afraid "referential >> integrity" may lead readers to think about foreign keys. Maybe it'd be >> better to explain this is about having index pointers to the new tuple >> version, etc. >> >> 2) Wouldn't it be good to make it a bit more explicit we now have three >> "levels" of HOT: >> >> (a) no indexes need update >> (b) update only summarizing indexes >> (c) update all indexes >> >> The original text was really about on/off, and I'm not quite sure the >> part about "exception" makes this very clear. > > Agreed on both points. Attached an updated version which incorporates > your points. > Thanks, pushed after correcting a couple typos. regards -- Tomas Vondra EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
On Fri, 7 Jul 2023 at 19:06, Tomas Vondra <tomas.vondra@enterprisedb.com> wrote: > > On 7/7/23 18:34, Matthias van de Meent wrote: > > On Fri, 7 Jul 2023 at 00:14, Tomas Vondra <tomas.vondra@enterprisedb.com> wrote: > >> The original text was really about on/off, and I'm not quite sure the > >> part about "exception" makes this very clear. > > > > Agreed on both points. Attached an updated version which incorporates > > your points. > > > > Thanks, pushed after correcting a couple typos. Thanks! Kind regards, Matthias van de Meent Neon (https://neon.tech)
Hi, > > Thanks, pushed after correcting a couple typos. > > Thanks! I noticed that ec99d6e9c87a introduced a slight typo: s/if there is not room/if there is no room -- Best regards, Aleksander Alekseev