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perf: use LATERAL instead of CTE for json body

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* add pgbench test for INSERT and RPC
* use LATERAL for RPC and INSERT
* add tests for inlining
This commit is contained in:
steve-chavez
2023-02-25 15:01:06 -05:00
committed by Steve Chavez
parent 253f2bf537
commit 0d5d209bfb
11 changed files with 144 additions and 97 deletions
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src/PostgREST/Query/SqlFragment.hs
+22 -36
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@@ -21,7 +21,6 @@ module PostgREST.Query.SqlFragment
, limitOffsetF
, locationF
, mutRangeF
, normalizedBody
, orderF
, pgFmtColumn
, pgFmtIdent
@@ -30,11 +29,10 @@ module PostgREST.Query.SqlFragment
, pgFmtLogicTree
, pgFmtOrderTerm
, pgFmtSelectItem
, pgFmtSelectFromJson
, fromJsonBodyF
, responseHeadersF
, responseStatusF
, returningF
, selectBody
, singleParameter
, sourceCTEName
, unknownEncoder
@@ -121,25 +119,6 @@ ftsOperator = \case
FilterFtsPhrase -> "@@ phraseto_tsquery"
FilterFtsWebsearch -> "@@ websearch_to_tsquery"
-- |
-- These CTEs convert a json object into a json array, this way we can use json_to_recordset for all json payloads
-- Otherwise we'd have to use json_to_record for json objects and json_to_recordset for json arrays
-- We do this in SQL to avoid processing the JSON in application code
-- TODO: At this stage there shouldn't be a Maybe since ApiRequest should ensure that an INSERT/UPDATE has a body
normalizedBody :: Maybe LBS.ByteString -> SQL.Snippet
normalizedBody body =
"pgrst_payload AS (SELECT " <> jsonPlaceHolder <> " AS json_data), " <>
SQL.sql (BS.unwords [
"pgrst_body AS (",
"SELECT",
"CASE WHEN json_typeof(json_data) = 'array'",
"THEN json_data",
"ELSE json_build_array(json_data)",
"END AS val",
"FROM pgrst_payload)"])
where
jsonPlaceHolder = SQL.encoderAndParam (HE.nullable HE.jsonLazyBytes) body
singleParameter :: Maybe LBS.ByteString -> ByteString -> SQL.Snippet
singleParameter body typ =
if typ == "bytea"
@@ -147,9 +126,6 @@ singleParameter body typ =
then SQL.encoderAndParam (HE.nullable HE.bytea) (LBS.toStrict <$> body)
else SQL.encoderAndParam (HE.nullable HE.unknown) (LBS.toStrict <$> body) <> "::" <> SQL.sql typ
selectBody :: SqlFragment
selectBody = "(SELECT val FROM pgrst_body)"
-- Here we build the pg array literal, e.g '{"Hebdon, John","Other","Another"}', manually.
-- This is necessary to pass an "unknown" array and let pg infer the type.
-- There are backslashes here, but since this value is parametrized and is not a string constant
@@ -244,19 +220,29 @@ pgFmtSelectItem table (f@(fName, jp), Nothing, alias) = pgFmtField table f <> SQ
-- Not quoting should be fine, we validate the input on Parsers.
pgFmtSelectItem table (f@(fName, jp), Just cast, alias) = "CAST (" <> pgFmtField table f <> " AS " <> SQL.sql (encodeUtf8 cast) <> " )" <> SQL.sql (pgFmtAs fName jp alias)
pgFmtSelectFromJson :: [TypedField] -> SQL.Snippet
pgFmtSelectFromJson fields =
SQL.sql "SELECT " <> parsedCols <> " " <>
(if null fields
-- When we are inserting no columns (e.g. using default values), we can't use our ordinary `json_to_recordset`
-- because it can't extract records with no columns (there's no valid syntax for the `AS (colName colType,...)`
-- part). But we still need to ensure as many rows are created as there are array elements.
then SQL.sql ("FROM json_array_elements (" <> selectBody <> ") _ ")
else SQL.sql ("FROM json_to_recordset (" <> selectBody <> ") AS _ " <> "(" <> typedCols <> ") ")
)
-- TODO: At this stage there shouldn't be a Maybe since ApiRequest should ensure that an INSERT/UPDATE has a body
fromJsonBodyF :: Maybe LBS.ByteString -> [TypedField] -> Bool -> Bool -> SQL.Snippet
fromJsonBodyF body fields includeSelect includeLimitOne =
SQL.sql
(if includeSelect then "SELECT " <> parsedCols <> " " else mempty) <>
"FROM (SELECT " <> jsonPlaceHolder <> " AS json_data) pgrst_payload, " <>
-- convert a json object into a json array, this way we can use json_to_recordset for all json payloads
-- Otherwise we'd have to use json_to_record for json objects and json_to_recordset for json arrays
-- We do this in SQL to avoid processing the JSON in application code
"LATERAL (SELECT CASE WHEN json_typeof(pgrst_payload.json_data) = 'array' THEN pgrst_payload.json_data ELSE json_build_array(pgrst_payload.json_data) END AS val) pgrst_uniform_json, " <>
"LATERAL (SELECT * FROM " <>
(if null fields
-- When we are inserting no columns (e.g. using default values), we can't use our ordinary `json_to_recordset`
-- because it can't extract records with no columns (there's no valid syntax for the `AS (colName colType,...)`
-- part). But we still need to ensure as many rows are created as there are array elements.
then SQL.sql "json_array_elements(pgrst_uniform_json.val) _ "
else SQL.sql ("json_to_recordset(pgrst_uniform_json.val) AS _(" <> typedCols <> ") " <> if includeLimitOne then "LIMIT 1" else mempty)
) <>
") pgrst_body "
where
parsedCols = SQL.sql $ BS.intercalate ", " $ pgFmtIdent . tfName <$> fields
parsedCols = BS.intercalate ", " $ fromQi . QualifiedIdentifier "pgrst_body" . tfName <$> fields
typedCols = BS.intercalate ", " $ pgFmtIdent . tfName <> const " " <> encodeUtf8 . tfIRType <$> fields
jsonPlaceHolder = SQL.encoderAndParam (HE.nullable HE.jsonLazyBytes) body
pgFmtOrderTerm :: QualifiedIdentifier -> OrderTerm -> SQL.Snippet
pgFmtOrderTerm qi ot =