09a5c8028e
Check whether the `op` condition is null rejected, if yes, derive `col is not null` for both sides of inner join, and for inner side of outer join. Also, remove duplicate conditions before pushing them down. Check if the condition is mutable before removing duplicates. For AntiSemiJoin, AntiLeftOuterSemiJoin and LeftOuterSemiJoin, do not generate new `is not null` conditions.
107 lines
3.4 KiB
Go
107 lines
3.4 KiB
Go
// Copyright 2017 PingCAP, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package expression
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import (
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"github.com/pingcap/parser/ast"
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)
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// UnCacheableFunctions stores functions which can not be cached to plan cache.
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var UnCacheableFunctions = map[string]struct{}{
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ast.Database: {},
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ast.CurrentUser: {},
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ast.User: {},
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ast.ConnectionID: {},
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ast.LastInsertId: {},
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ast.Version: {},
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ast.Like: {},
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}
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// unFoldableFunctions stores functions which can not be folded duration constant folding stage.
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var unFoldableFunctions = map[string]struct{}{
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ast.Sysdate: {},
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ast.FoundRows: {},
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ast.Rand: {},
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ast.UUID: {},
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ast.Sleep: {},
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ast.RowFunc: {},
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ast.Values: {},
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ast.SetVar: {},
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ast.GetVar: {},
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ast.GetParam: {},
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}
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// DeferredFunctions stores non-deterministic functions, which can be deferred only when the plan cache is enabled.
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var DeferredFunctions = map[string]struct{}{
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ast.Now: {},
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ast.CurrentTimestamp: {},
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ast.UTCTime: {},
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ast.Curtime: {},
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ast.CurrentTime: {},
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ast.UTCTimestamp: {},
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ast.UnixTimestamp: {},
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ast.Sysdate: {},
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ast.Curdate: {},
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ast.CurrentDate: {},
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ast.UTCDate: {},
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ast.Rand: {},
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ast.UUID: {},
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}
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// inequalFunctions stores functions which cannot be propagated from column equal condition.
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var inequalFunctions = map[string]struct{}{
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ast.IsNull: {},
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}
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// mutableEffectsFunctions stores functions which are mutable or have side effects, specifically,
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// we cannot remove them from filter even if they have duplicates.
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var mutableEffectsFunctions = map[string]struct{}{
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// Time related functions in MySQL have various behaviors when executed multiple times in a single SQL,
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// for example:
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// mysql> select current_timestamp(), sleep(5), current_timestamp();
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// +---------------------+----------+---------------------+
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// | current_timestamp() | sleep(5) | current_timestamp() |
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// +---------------------+----------+---------------------+
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// | 2018-12-18 17:55:39 | 0 | 2018-12-18 17:55:39 |
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// +---------------------+----------+---------------------+
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// while:
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// mysql> select sysdate(), sleep(5), sysdate();
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// +---------------------+----------+---------------------+
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// | sysdate() | sleep(5) | sysdate() |
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// +---------------------+----------+---------------------+
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// | 2018-12-18 17:57:38 | 0 | 2018-12-18 17:57:43 |
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// +---------------------+----------+---------------------+
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// for safety consideration, treat them all as mutable.
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ast.Now: {},
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ast.CurrentTimestamp: {},
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ast.UTCTime: {},
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ast.Curtime: {},
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ast.CurrentTime: {},
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ast.UTCTimestamp: {},
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ast.UnixTimestamp: {},
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ast.Sysdate: {},
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ast.Curdate: {},
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ast.CurrentDate: {},
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ast.UTCDate: {},
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ast.Rand: {},
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ast.RandomBytes: {},
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ast.UUID: {},
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ast.UUIDShort: {},
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ast.Sleep: {},
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ast.SetVar: {},
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ast.GetVar: {},
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ast.AnyValue: {},
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}
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