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MDEV-7773: Aggregate stored functions

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This commit implements aggregate stored functions. The basic idea behind
the feature is:

* Implement a special instruction FETCH GROUP NEXT ROW that will pause
the execution of the stored function. When the instruction is reached,
execution of the initial query resumes "as if" the function returned.
This gives the server the opportunity to advance to the next row in the
result set.

* Stored aggregates behave like regular aggregate functions. The
implementation of thus resides in the class Item_sum_sp. Because it is
an aggregate function, for each new row in the group, the
Item_sum_sp::add() method will be called. This is when execution resumes
and the function does another iteration to "add" one extra element to
the final result.

* When the end of group is reached, val_xxx() method will be called for
the item. This case is handled by another execute step for the stored
function, only with a special flag to force a call to the return
handler. See Item_sum_sp::execute() for details.

To allow this pause and resume semantic, we must preserve the function
context across executions. This is stored in Item_sp::sp_query_arena only for
aggregate stored functions, but has no impact for regular functions.

We also enforce aggregate functions to include the "FETCH GROUP NEXT ROW"
instruction.

Signed-off-by: Vicențiu Ciorbaru <vicentiu@mariadb.org>
This commit is contained in:
Varun Gupta
2017-11-22 21:09:24 +02:00
committed by Vicențiu Ciorbaru
parent 7448b01bb5
commit 60c446584c
33 changed files with 2307 additions and 84 deletions
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2
mysql-test/suite/funcs_1/r/is_columns_mysql_embedded.result
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@ -119,6 +119,7 @@ def mysql index_stats prefix_arity 4 NULL NO int NULL NULL 10 0 NULL NULL NULL i
def mysql index_stats table_name 2 NULL NO varchar 64 192 NULL NULL NULL utf8 utf8_bin varchar(64) PRI NEVER NULL
def mysql plugin dl 2 '' NO varchar 128 384 NULL NULL NULL utf8 utf8_general_ci varchar(128) NEVER NULL
def mysql plugin name 1 '' NO varchar 64 192 NULL NULL NULL utf8 utf8_general_ci varchar(64) PRI NEVER NULL
def mysql proc aggregate 21 'NONE' NO enum 5 15 NULL NULL NULL utf8 utf8_general_ci enum('NONE','GROUP') NEVER NULL
def mysql proc body 11 NULL NO longblob 4294967295 4294967295 NULL NULL NULL NULL NULL longblob NEVER NULL
def mysql proc body_utf8 20 NULL YES longblob 4294967295 4294967295 NULL NULL NULL NULL NULL longblob NEVER NULL
def mysql proc character_set_client 17 NULL YES char 32 96 NULL NULL NULL utf8 utf8_bin char(32) NEVER NULL
@ -472,6 +473,7 @@ NULL mysql proc modified timestamp NULL NULL NULL NULL timestamp
3.0000 mysql proc collation_connection char 32 96 utf8 utf8_bin char(32)
3.0000 mysql proc db_collation char 32 96 utf8 utf8_bin char(32)
1.0000 mysql proc body_utf8 longblob 4294967295 4294967295 NULL NULL longblob
3.0000 mysql proc aggregate enum 5 15 utf8 utf8_general_ci enum('NONE','GROUP')
3.0000 mysql procs_priv Host char 60 180 utf8 utf8_bin char(60)
3.0000 mysql procs_priv Db char 64 192 utf8 utf8_bin char(64)
3.0000 mysql procs_priv User char 80 240 utf8 utf8_bin char(80)