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Large Object Heap Fragmentation
...is is a very interesting lead, thanks. Completely forgot about the intern table. I know one of our developers is a keen interner so this is definitely something I shall investigate.
– Paul Ruane
Mar 27 '09 at 10:34
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How efficient is locking an unlocked mutex? What is the cost of a mutex?
... system limit. But too many of them spells nightmare for debugging. Simple table:
Less locks means more contentions (slow syscalls, CPU stalls) and lesser parallelism
Less locks means less problems debugging multi-threading problems.
More locks means less contentions and higher parallelism
More lo...
How do you run a single query through mysql from the command line?
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mysql -u <user> -p -e "select * from schema.table"
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How to display the function, procedure, triggers source code in postgresql?
.... Just know the following way, may be it will help you!
step 1 : Get the table oid of the trigger:
skytf=> select tgrelid from pg_trigger where tgname='insert_tbl_tmp_trigger';
tgrelid
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26599
(1 row)
step 2: Get the table name of the above oid !
s...
Is it safe to parse a /proc/ file?
...s even less consistent than that. It's atomic only within each row of the table. To see this, look at listening_get_next() in net/ipv4/tcp_ipv4.c and established_get_next() just below in the same file, and see the locks they take out on each entry in turn. I don't have repro code handy to demonst...
Disable spell-checking on HTML textfields
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MDN has a table showing the default value of spellcheck for different browsers and elements: developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/…
– Paul
Jan 31 '17 at 17:39
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SQL Server: Examples of PIVOTing String data
...on will work on text as well as numbers. This query will only require the table to be scanned once.
SELECT Action,
MAX( CASE data WHEN 'View' THEN data ELSE '' END ) ViewCol,
MAX( CASE data WHEN 'Edit' THEN data ELSE '' END ) EditCol
FROM t
GROUP BY Action
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How to set top-left alignment for UILabel for iOS application?
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Works like a charm, even in a UITableViewCell with reuse.
– alex.bour
Jun 10 '16 at 8:53
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SQL中使用update inner join和delete inner join；Oracle delete join替代...
...> 0
and mw.size > 1;
下面是Oracle的：
Sql代码
DELETE TABLE1 where KHID exists ( select KHID from table2 where FWDWID=8)
Sql代码
DELETE TABLE1 where exists ( select 1 from table2 where and table1.khid=table2.khid and FWDWID=8);
Oracle的delete与join如何使用
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Rails migrations: self.up and self.down versus change
... you rollback? Of course it's remove_column. What is the inverse of create_table? It's drop_table. So in these cases rails know how to rollback and define a down method is superfluous (you can see in the documentation the methods currently supported from the change method).
But pay attention becaus...