From d5debc63bf27a96f43886b34d969bc8e648f7d6a Mon Sep 17 00:00:00 2001
From: Alec Strong <AlecStrong@users.noreply.github.com>
Date: Sat, 16 Apr 2022 19:20:25 -0400
Subject: [PATCH] Support MySQL index hints (#3099)

---
 .../dialects/mysql/grammar/MySql.bnf          | 27 ++++++++++++++++
 .../test/fixtures_mysql/index-hints/Test.s    | 31 +++++++++++++++++++
 2 files changed, 58 insertions(+)
 create mode 100644 dialects/mysql/src/test/fixtures_mysql/index-hints/Test.s

diff --git a/dialects/mysql/src/main/kotlin/app/cash/sqldelight/dialects/mysql/grammar/MySql.bnf b/dialects/mysql/src/main/kotlin/app/cash/sqldelight/dialects/mysql/grammar/MySql.bnf
index 67f05cf1f9ad..364aa9f14cb9 100644
--- a/dialects/mysql/src/main/kotlin/app/cash/sqldelight/dialects/mysql/grammar/MySql.bnf
+++ b/dialects/mysql/src/main/kotlin/app/cash/sqldelight/dialects/mysql/grammar/MySql.bnf
@@ -44,6 +44,8 @@ overrides ::= type_name
   | table_constraint
   | default_constraint
   | table_option
+  | table_or_subquery
+  | qualified_table_name
   | extension_stmt
   | alter_table_rules
   | alter_table_add_column
@@ -164,6 +166,31 @@ table_option ::= 'ENGINE' ['='] {identifier} |
 
 row_format_clause ::= 'ROW_FORMAT' [ '=' ] ( DEFAULT | 'DYNAMIC' | 'FIXED' | 'COMPRESSED' | 'REDUNDANT' | 'COMPACT' )
 
+table_or_subquery ::= ( [ {database_name} '.' ] {table_name} [ [ 'AS' ] {table_alias} ] [ index_hint_list ]
+                      | '(' ( {table_or_subquery} ( ',' {table_or_subquery} ) * | {join_clause} ) ')'
+                      | '(' {compound_select_stmt} ')' [ [ 'AS' ] {table_alias} ] ) {
+  extends = "com.alecstrong.sql.psi.core.psi.impl.SqlTableOrSubqueryImpl"
+  implements = "com.alecstrong.sql.psi.core.psi.SqlTableOrSubquery"
+  override = true
+}
+
+qualified_table_name ::= [ {database_name} '.' ] {table_name} [ index_hint_list ] {
+  extends = "com.alecstrong.sql.psi.core.psi.impl.SqlQualifiedTableNameImpl"
+  implements = "com.alecstrong.sql.psi.core.psi.SqlQualifiedTableName"
+  override = true
+}
+
+index_hint_list ::= index_hint ( index_hint ) *
+
+index_hint ::=
+  ( 'USE' ( 'INDEX' | 'KEY' ) [ 'FOR' ( 'JOIN' | 'ORDER' 'BY' | 'GROUP' 'BY' )] [index_list] )
+  |
+  ( ('IGNORE' | 'FORCE' ) ( 'INDEX' | 'KEY' ) [ 'FOR' ( 'JOIN' | 'ORDER' 'BY' | 'GROUP' 'BY' )] index_list ) {
+  pin = 1
+}
+
+index_list ::= '(' {index_name} ( ',' {index_name} ) * ')'
+
 alter_table_rules ::= (
   alter_table_add_column
   | {alter_table_rename_table}
diff --git a/dialects/mysql/src/test/fixtures_mysql/index-hints/Test.s b/dialects/mysql/src/test/fixtures_mysql/index-hints/Test.s
new file mode 100644
index 000000000000..bed7cc58ee26
--- /dev/null
+++ b/dialects/mysql/src/test/fixtures_mysql/index-hints/Test.s
@@ -0,0 +1,31 @@
+CREATE TABLE t1(
+  a VARCHAR(8) NOT NULL
+);
+
+CREATE INDEX i1 ON t1(a);
+
+CREATE INDEX i2 ON t1(a);
+
+SELECT * FROM t1 USE INDEX;
+
+SELECT * FROM t1 USE INDEX (i1) IGNORE INDEX FOR ORDER BY (i2) ORDER BY a;
+
+SELECT * FROM t1 USE INDEX (i1) USE INDEX (i1,i1);
+
+SELECT * FROM t1 USE INDEX FOR JOIN (i1) FORCE INDEX FOR JOIN (i2);
+
+CREATE TABLE table1(
+  col1 TEXT,
+  col2 TEXT,
+  col3 TEXT
+);
+
+CREATE INDEX col1_index ON table1(col1);
+CREATE INDEX col2_index ON table1(col2);
+CREATE INDEX col3_index ON table1(col3);
+
+SELECT * FROM table1 USE INDEX (col1_index,col2_index)
+  WHERE col1=1 AND col2=2 AND col3=3;
+
+SELECT * FROM table1 IGNORE INDEX (col3_index)
+  WHERE col1=1 AND col2=2 AND col3=3;
\ No newline at end of file