MDEV-34391 SET PATH statement

Definition
==========
Implement the SET PATH statement. The grammar differs from the Jira
ticket where the equal sign is required:
```
SET PATH= 'schema1, schema2, schema3';
```

Function
--------
In MariaDB, the SQL-path will also be used to lookup packages in
package routine invocations, so the following script:

  SET PATH='sys';
  SELECT UTL_ENCODE.BASE64_DECODE('data');

invokes SYS.UTL_ENCODE.BASE64_DECODE('data'), i.e. the function
BASE64_DECODE() in the packge UTL_ENCODE in the database SYS
(if such package and package routine exist).

MariaDB implementation details
------------------------------
The ticket's requirement stated the grammar should support delimited
identifiers with backticks or double quotes within the string quote,
ie: the single tick. A simple parser was implemented to handle this
requirement in Sql_path::from_text.

Only 16 schemas are supported per session - we do not want too many
schemas in the path anyway since it will impact performance. This also
means that the path cache is a simple static array for easier memory
management.

Internal schemas (mariadb_schema, oracle_schema) are supported in paths.
Only the first internal schema in the path will be used to resolve native
routines to their respective versions.

libmysqld/CMakeLists.txt

@@ -156,6 +156,7 @@ SET(SQL_EMBEDDED_SOURCES emb_qcache.cc libmysqld.c lib_sql.cc
            ../sql/json_table.cc
            ../sql/opt_histogram_json.cc
            ../sql/sp_instr.cc
+           ../sql/sql_path.cc
            ${GEN_SOURCES}
            ${MYSYS_LIBWRAP_SOURCE}
 )

mysql-test/include/commit.inc

@@ -413,7 +413,7 @@ flush status;
 
 --echo #
 --echo # Count of reading of p_verify_status_increment() from mysql.proc
-call p_verify_status_increment(2, 0, 2, 0);
+call p_verify_status_increment(4, 0, 2, 0);
 
 --echo #
 --echo # 1. Read-only statement: SELECT
@@ -581,7 +581,7 @@ call p_verify_status_increment(4, 0, 4, 0);
 --echo # the binary log. 
 --echo #
 select f1();
-call p_verify_status_increment(3, 0, 3, 0);
+call p_verify_status_increment(5, 0, 3, 0);
 commit;
 call p_verify_status_increment(1, 0, 1, 0);
 
@@ -620,14 +620,20 @@ create temporary table t2 (a int);
 # One commit for the create temporary table, and two for committing the
 # read of the stored procedure from Aria table (creating temporary table
 # clears the sp cache).
-call p_verify_status_increment(3, 0, 2, 0);
+# After the sp cache cleard, another two commits increased due to the read
+# of the stored procedure from mysql.proc table during the invocation of
+# p_verify_status_increment() with using new sql path resolution mechanism.
+call p_verify_status_increment(5, 0, 2, 0);
 set sql_mode=default;
 --echo # 19. A function changes temp-trans-table.
 --echo #
 select f1();
 --echo # Two commits because a binary log record is written, and another two
 --echo # as the function f1() is reloaded after creating temporary table.
-call p_verify_status_increment(4, 0, 3, 0);
+--echo # After the function f1() is reloaded, another two commits increased due
+--echo # to the read of the stored procedure from mysql.proc table during the
+--echo # invocation of f1() with using new sql path resolution mechanism.
+call p_verify_status_increment(6, 0, 3, 0);
 commit;
 call p_verify_status_increment(2, 0, 1, 0);
 
@@ -682,7 +688,10 @@ call p_verify_status_increment(2, 0, 1, 0);
 drop temporary table t2;
 # Dropping temporary table clears SP caches, so get another two commit
 # increments from loading the p_verify_status_increment procedure.
-call p_verify_status_increment(3, 0, 2, 0);
+# After the sp cache cleard, another two commits increased due to the read
+# of the stored procedure from mysql.proc table during the invocation of
+# p_verify_status_increment() with using new sql path resolution mechanism.
+call p_verify_status_increment(5, 0, 2, 0);
 commit;
 call p_verify_status_increment(1, 0, 0, 0);
 
@@ -733,7 +742,10 @@ call p_verify_status_increment(0, 0, 0, 0);
 do (select f1() from t1 where a=2);
 # Again extra 2 commit increments from re-loading function f1 after
 # dropping temporary table.
-call p_verify_status_increment(4, 2, 4, 2);
+# After the function f1() is reloaded, another two commits increased due
+# to the read of the stored procedure from mysql.proc table during the
+# invocation of f1() with using new sql path resolution mechanism.
+call p_verify_status_increment(6, 2, 4, 2);
 commit;
 call p_verify_status_increment(2, 2, 2, 2);
 

mysql-test/include/deselect_db.inc

@@ -0,0 +1,4 @@
+# Drop the current db. This de-selects any db.
+CREATE DATABASE deselect_db;
+USE deselect_db;
+DROP DATABASE deselect_db;

mysql-test/main/commit_1innodb.result

@@ -387,7 +387,7 @@ end|
 flush status;
 #
 # Count of reading of p_verify_status_increment() from mysql.proc
-call p_verify_status_increment(2, 0, 2, 0);
+call p_verify_status_increment(4, 0, 2, 0);
 SUCCESS
 
 #
@@ -585,7 +585,7 @@ SUCCESS
 select f1();
 f1()
 2
-call p_verify_status_increment(3, 0, 3, 0);
+call p_verify_status_increment(5, 0, 3, 0);
 SUCCESS
 
 commit;
@@ -634,7 +634,7 @@ SUCCESS
 drop table t2;
 set sql_mode=no_engine_substitution;
 create temporary table t2 (a int);
-call p_verify_status_increment(3, 0, 2, 0);
+call p_verify_status_increment(5, 0, 2, 0);
 SUCCESS
 
 set sql_mode=default;
@@ -645,7 +645,10 @@ f1()
 2
 # Two commits because a binary log record is written, and another two
 # as the function f1() is reloaded after creating temporary table.
-call p_verify_status_increment(4, 0, 3, 0);
+# After the function f1() is reloaded, another two commits increased due
+# to the read of the stored procedure from mysql.proc table during the
+# invocation of f1() with using new sql path resolution mechanism.
+call p_verify_status_increment(6, 0, 3, 0);
 SUCCESS
 
 commit;
@@ -716,7 +719,7 @@ SUCCESS
 # 25. DDL: DROP TEMPORARY TABLE, does not start a transaction
 #
 drop temporary table t2;
-call p_verify_status_increment(3, 0, 2, 0);
+call p_verify_status_increment(5, 0, 2, 0);
 SUCCESS
 
 commit;
@@ -802,7 +805,7 @@ call p_verify_status_increment(0, 0, 0, 0);
 SUCCESS
 
 do (select f1() from t1 where a=2);
-call p_verify_status_increment(4, 2, 4, 2);
+call p_verify_status_increment(6, 2, 4, 2);
 SUCCESS
 
 commit;

mysql-test/main/lock_sync.result

@@ -743,13 +743,17 @@ CREATE VIEW v1 AS SELECT * FROM t1 WHERE f1() = 1;
 DROP FUNCTION f1;
 connect con2, localhost, root;
 connect  con1, localhost, root;
-SET DEBUG_SYNC= 'open_tables_after_open_and_process_table SIGNAL opened WAIT_FOR dropped EXECUTE 2';
+SET DEBUG_SYNC= 'open_tables_after_open_and_process_table SIGNAL opened WAIT_FOR dropped EXECUTE 4';
 # Sending:
 SHOW CREATE VIEW v1;
 connection con2;
 SET DEBUG_SYNC= 'now WAIT_FOR opened';
 SET DEBUG_SYNC= 'now SIGNAL dropped';
 SET DEBUG_SYNC= 'now WAIT_FOR opened';
+SET DEBUG_SYNC= 'now SIGNAL dropped';
+SET DEBUG_SYNC= 'now WAIT_FOR opened';
+SET DEBUG_SYNC= 'now SIGNAL dropped';
+SET DEBUG_SYNC= 'now WAIT_FOR opened';
 # Sending:
 FLUSH TABLES t1;
 connection default;

mysql-test/main/lock_sync.test

@@ -947,14 +947,20 @@ connect(con2, localhost, root);
 connect (con1, localhost, root);
 # Need to trigger this sync point at least twice in order to
 # get valgrind test failures without the patch
-SET DEBUG_SYNC= 'open_tables_after_open_and_process_table SIGNAL opened WAIT_FOR dropped EXECUTE 2';
+SET DEBUG_SYNC= 'open_tables_after_open_and_process_table SIGNAL opened WAIT_FOR dropped EXECUTE 4';
 --echo # Sending:
 --send SHOW CREATE VIEW v1
 
 connection con2;
 SET DEBUG_SYNC= 'now WAIT_FOR opened';
 SET DEBUG_SYNC= 'now SIGNAL dropped';
 SET DEBUG_SYNC= 'now WAIT_FOR opened';
+# Increase the count of sync point to 4 from 2 due to the new sql path
+# need to perform the db + routine/package lookup
+SET DEBUG_SYNC= 'now SIGNAL dropped';
+SET DEBUG_SYNC= 'now WAIT_FOR opened';
+SET DEBUG_SYNC= 'now SIGNAL dropped';
+SET DEBUG_SYNC= 'now WAIT_FOR opened';
 --echo # Sending:
 --send FLUSH TABLES t1
 

mysql-test/main/mysqld--help.result

@@ -915,6 +915,7 @@ The following specify which files/extra groups are read (specified before remain
  Cost of checking the row against the WHERE clause.
  Increasing this will have the optimizer to prefer plans
  with less row combinations
+ --path=name         SET PATH statement
  --performance-schema 
  Enable the performance schema
  --performance-schema-accounts-size=# 
@@ -1885,6 +1886,7 @@ optimizer-trace
 optimizer-trace-max-mem-size 1048576
 optimizer-use-condition-selectivity 4
 optimizer-where-cost 0.032
+path (No default value)
 performance-schema FALSE
 performance-schema-accounts-size -1
 performance-schema-consumer-events-stages-current FALSE