Timeline for Why correlated scalar is 10x times slower in MySQL comparing to PG
Current License: CC BY-SA 4.0
12 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Oct 5 at 8:00 | vote | accept | Slimboy Fat | ||
| Oct 3 at 21:29 | comment | added | Frank Heikens | Sorry, can't help you with this. I try to stay away from MySQL... | |
| Oct 3 at 20:00 | comment | added | Slimboy Fat | @FrankHeikens Let's put PG out of the picture. If you can make it run several times faster in MySQL - please add your solution to dba.stackexchange.com/questions/347894/… | |
| Oct 3 at 19:58 | comment | added | Slimboy Fat | @Zegarek Finally, I wanted to thank you for answers and comments in my threads. I really appreciate the value you add. Thanks, man. | |
| Oct 3 at 19:57 | comment | added | Slimboy Fat | @Zegarek Another possible answer to “why” is because historically MySQL was targeted to OLTP workloads while PG evolved in both OLTP and OLAP areas. Practically speaking, MySQL can compete with PG only for strict OLTP workloads. Anyways, I raised more specific question on DBA site - dba.stackexchange.com/questions/347894/… | |
| Oct 3 at 19:57 | comment | added | Slimboy Fat | @Zegarek Absolutely agree with you. Most likely, in order to find the root cause, I need to profile C code. However, I had a hope that some MySQL experts can explain architectural specifics. I suspected that slowness might be due to MVCC implementation in MySQL. However it is somewhat similar to Oracle (with UNDO to reconstruct specific versions and LRU to get data from buffer) and query execution time in Oracle is even better than the one in PostgreSQL. Also I suspected it might be something related to prefetch. | |
| Oct 3 at 19:40 | comment | added | Frank Heikens | Did you check your configuration? MySQL might be more sensitive to a suboptimal configuration. See also dba.stackexchange.com/questions/27328/… | |
| Oct 3 at 13:51 | comment | added | Zegarek | I don't think "it's slower" is a good answer to "why is it slower". This post somewhat simplifies the problem or takes a step in the right direction by peeling away a redundant layer, focusing on the scan that seems to be the leading factor in the overall query cost. However, it doesn't answer the question you posed, only reiterates it. As an edit to expand the question (or rather clean it up and simplify), it could be more helpful. Also, posting a (non-)answer hides this thread from people's feeds, so you're losing possibly valuable traffic. | |
| Oct 3 at 11:51 | history | undeleted | Slimboy Fat | ||
| Oct 3 at 11:51 | history | edited | Slimboy Fat | CC BY-SA 4.0 |
added 2740 characters in body
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| Oct 3 at 11:16 | history | deleted | Slimboy Fat | via Vote | |
| Oct 3 at 11:16 | history | answered | Slimboy Fat | CC BY-SA 4.0 |