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Fix json_build_object with tables with more than 50 columns #23

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Fix json_build_object with tables with more than 50 columns #23

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10 changes: 10 additions & 0 deletions server/src-lib/Hasura/Backends/Postgres/Execute/Subscription.hs
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Original file line number Diff line number Diff line change
Expand Up @@ -358,6 +358,16 @@ mkStreamingMultiplexedQuery userInfo (fieldAlias, resolvedAST) = do
[resultIdAlias, resultVarsAlias]

-- json_build_object('field1', field1.root, 'field2', field2.root, ...)
-- json_build_object should not be used without array https://postgrespro.com/list/thread-id/2486891
-- Please someone with proper Haskel knowledge change this)
-- Postgres has a limitation of maximum 100 function arguments
-- If you have a table with 50 columns this code produces 100 arguments in the json_build_object and postgres throws error
-- And you can't increase this limit in Postgres, the only way is to compile your own version of postgres which is stupid to do otherwise such configuraton can't be done
-- Same change needs to be done not just in subscription but in othe rplaces as well where json_build is used
-- From what I understood to fix this should be enough to do something like json_object(array[..,..,..])
--- Found this in this discussion https://postgrespro.com/list/thread-id/2486891
-- At the moment Hasura just can't be used with tables with more that 50 columns which is a huge limitation
-- And you have to unecessarelly split tables, I don't even talk about adding computed fields which these also counts as arguments
rootFieldJsonAggregate = S.SEFnApp "json_build_object" rootFieldJsonPair Nothing
rootFieldJsonPair =
[ S.SELit (G.unName fieldAlias),
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