Fix for count being very slow on large Parse Classes' collections #5264
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… much more effecient estimatedDocumentCount if no queries were specified
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## master #5264 +/- ##
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- Coverage 93.88% 93.85% -0.03%
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Files 123 123
Lines 8971 8973 +2
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Hits 8422 8422
- Misses 549 551 +2
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ghost
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This is a reasonable solution :) thanks for the PR! |
flovilmart
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Dec 28, 2018
UnderratedDev
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Mar 21, 2020
…rse-community#5264) * * Added fix for MongoCollection's count function, so that it uses the much more effecient estimatedDocumentCount if no queries were specified * * Added missing options when running estimatedDocumentCount for Mongo Collections * * Fixed issue with checking for zero query for Mongo Collections count
NicksonYap
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For newer version of parse-server (at least 3.1.2) fetching count for a Parse Class takes a very long time if the Class has lots (1M+) of rows.
This is due to the Parse-Server's internal MongoCollection class using mongoDb's db.collection.countDocuments() method, which causes all of the collection's documents to be scanned; thus making the operation extremely slow.
This should be fixed so that countDocuments is only used for counting if a query is also provided. Otherwise the much faster db.collection.estimatedDocumentCount() should be used instead.
In the PR I've updated
MongoCollection.count(...)so that if no query is specified, then the counting is done by theestimatedDocumentCount()method.This problem has previously been discussed in issue #5218, and similar performance issues have been discussed here for mongoose.