Change GetClanDetailsQuery #59
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lgtm |
andrehp
suggested changes
Jun 3, 2020
andrehp
suggested changes
Jun 3, 2020
models/clan.go
Outdated
| @@ -805,7 +805,7 @@ func GetClanDetails(db DB, gameID string, clan *Clan, maxClansPerPlayer int, opt | |||
| UNION ALL ( | |||
| SELECT * | |||
| FROM memberships im | |||
| WHERE im.clan_id=$2 AND im.deleted_at=0 AND im.approved=false AND im.denied=false AND im.banned=false AND im.requestor_id<>im.player_id | |||
| WHERE im.clan_id=$2 AND im.deleted_at=0 AND im.approved=false AND im.denied=false AND im.banned=false AND (im.requestor_id>im.player_id OR im.requestor_id<im.player) | |||
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You are missing _id at the end of your query
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nice to see you around @andrehp! thanks for reviewing!
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I fixed the image :) |
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any reason not to merge this @leohahn ? |
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This very little change in the query has a huge impact on performance in postgresql as seen below. The reason is that the comparison using
<and>can better use the index and the comparison using<>needs to do a full index scan.This is the
QUERY PLANexecuted usingEXPLAIN ANALYZEon production DB before the change:As you can see in the image the execution time takes almost 2s because on step
Subquery Scan "SELECT* 2"it needs to do a scan to find the matches and the table has 3534350 entries.This is the
QUERY PLANafter the change:Now the execution time is 32ms because it doesn't need to do a full index scan and for this example it runs more than 20 times faster.