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EXAMPLE storage engine: update comments

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This commit is contained in:
Federico Razzoli
2023-08-14 20:56:27 +01:00
committed by Daniel Black
parent 0254eb9307
commit e666b8651a
2 changed files with 21 additions and 25 deletions
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16
storage/example/ha_example.cc
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@@ -38,7 +38,7 @@
build by doing the following during your build process:<br> ./configure
--with-example-storage-engine
Once this is done, MySQL will let you create tables with:<br>
Once this is done, MariaDB will let you create tables with:<br>
CREATE TABLE <table name> (...) ENGINE=EXAMPLE;
The example storage engine is set up to use table locks. It
@@ -51,9 +51,9 @@
of this file.
@note
When you create an EXAMPLE table, the MySQL Server creates a table .frm
When you create an EXAMPLE table, the MariaDB Server creates a table .frm
(format) file in the database directory, using the table name as the file
name as is customary with MySQL. No other files are created. To get an idea
name as is customary with MariaDB. No other files are created. To get an idea
of what occurs, here is an example select that would do a scan of an entire
table:
@@ -86,10 +86,6 @@
ha_example::open() would also have been necessary. Calls to
ha_example::extra() are hints as to what will be occuring to the request.
A Longer Example can be found called the "Skeleton Engine" which can be
found on TangentOrg. It has both an engine and a full build environment
for building a pluggable storage engine.
Happy coding!<br>
-Brian
*/
@@ -771,7 +767,7 @@ int ha_example::external_lock(THD *thd, int lock_type)
Before adding the lock into the table lock handler (see thr_lock.c),
mysqld calls store lock with the requested locks. Store lock can now
modify a write lock to a read lock (or some other lock), ignore the
lock (if we don't want to use MySQL table locks at all), or add locks
lock (if we don't want to use MariaDB table locks at all), or add locks
for many tables (like we do when we are using a MERGE handler).
Berkeley DB, for example, changes all WRITE locks to TL_WRITE_ALLOW_WRITE
@@ -781,7 +777,7 @@ int ha_example::external_lock(THD *thd, int lock_type)
When releasing locks, store_lock() is also called. In this case one
usually doesn't have to do anything.
In some exceptional cases MySQL may send a request for a TL_IGNORE;
In some exceptional cases MariaDB may send a request for a TL_IGNORE;
This means that we are requesting the same lock as last time and this
should also be ignored. (This may happen when someone does a flush
table when we have opened a part of the tables, in which case mysqld
@@ -1084,7 +1080,7 @@ static int show_func_example(MYSQL_THD thd, struct st_mysql_show_var *var,
var->value= buf; // it's of SHOW_VAR_FUNC_BUFF_SIZE bytes
my_snprintf(buf, SHOW_VAR_FUNC_BUFF_SIZE,
"enum_var is %lu, ulong_var is %lu, int_var is %d, "
"double_var is %f, %.6b", // %b is a MySQL extension
"double_var is %f, %.6b", // %b is a MariaDB/MySQL extension
srv_enum_var, srv_ulong_var, THDVAR(thd, int_var),
srv_double_var, "really");
return 0;