unexpected message 'unable to allocate memory from OS' when trying to get left(
<blob>, 10) if it's length between 8126433 and 8126433
---------------------------------------------------------------------------------------------------------------------------------------
Key: CORE-4065
URL: http://tracker.firebirdsql.org/browse/CORE-4065
Project: Firebird Core
Issue Type: Bug
Components: Engine
Reporter: Pavel Zotov
create database 'tb.fdb'; commit;
create sequence g;
commit;
create table c(id int, f char(31)); commit;
-- fill table `c` with IDs and character strings:
--=================================
insert into c select gen_id(g,1), f.rdb$field_name from rdb$fields
f,rdb$fields,rdb$relations; commit;
set blob all;
set stat on;
select left(x, 10) from (select list(f) x from (select f from c where
id<262144)) where x similar to '%$%';
LEFT
=================
0:5d
==============================================================================
LEFT:
RDB$VIEW_C
==============================================================================
Current memory = 348919064
Delta memory = 343949652
Max memory = 563184888
Elapsed time= 3.84 sec
Buffers = 1024
Reads = 13291
Writes 2332
Fetches = 1363855
SQL> select left(x, 10) from (select list(f) x from (select f from c where
id<262145)) where x similar to '%$%';
LEFT
=================
Statement failed, SQLSTATE = HY001
unable to allocate memory from operating system
-- NOTE: this message looks very strange because I have about 2 Gb RAM on
machine and Firebird consumes only ~384 Mb at the peak of this operation.
SQL> select sum(char_length(f)) from c where id<262144;
SUM
=====================
8126433 -- this is the value where we yet *CAN* get result of
list()
SQL> select sum(char_length(f)) from c where id<262145;
SUM
=====================
8126464 -- this is the value where we can *NOT* get result of
list()
1) What is the `magic` in the length of the blob that is to be processed via
SIMILAR TO ?
2) Why the trivial search of FIRST occurence of single '$' character
(moreover, it is just at the beginning of blob) is extremely slow (3.84 sec) ?
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