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Run MySQLDump without Locking Tables
...bles you can use the --single-transaction option:
--lock-tables, -l
Lock all tables before dumping them. The tables are locked with READ
LOCAL to allow concurrent inserts in the case of MyISAM tables. For
transactional tables such as InnoDB and BDB, --single-transaction is
a much better option, be...
Assign one struct to another in C
...ree() because they are automatic variables: en.wikipedia.org/wiki/Automatic_variable
– joshdoe
Jun 19 '12 at 16:32
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关于阿里云传输数据问题 - App Inventor 2 拓展 - 清泛IT社区，为创新赋能！
...文档的地址 ...
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How to Test a Concern in Rails
...t I have a Personable concern in my Rails 4 application which has a full_name method, how would I go about testing this using RSpec?
...
MySQL: Transactions vs Locking Tables
...is transferred. And the bank's account, into which they'll happily deposit all the service fees charged on the transaction. Given (as everyone knows these days) that banks are extraordinarily stupid, let's say their system works like this:
$balance = "GET BALANCE FROM your ACCOUNT";
if ($balance &l...
Python assigning multiple variables to same value? list behavior
...the same identical value. Variables have types, identities, addresses, and all kinds of stuff like that.
Names don't have any of that. Values do, of course, and you can have lots of names for the same value.
If you give Notorious B.I.G. a hot dog,* Biggie Smalls and Chris Wallace have a hot dog. ...
MongoDB - Update objects in a document's array (nested updating)
...reak it into two parts. First, increment any document that has "items.item_name" equal to "my_item_two". For this you'll have to use the positional "$" operator. Something like:
db.bar.update( {user_id : 123456 , "items.item_name" : "my_item_two" } ,
{$inc : {"items.$.price" : ...
postgresql COUNT(DISTINCT …) very slow
...
You can use this:
SELECT COUNT(*) FROM (SELECT DISTINCT column_name FROM table_name) AS temp;
This is much faster than:
COUNT(DISTINCT column_name)
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How do I reset a sequence in Oracle?
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alter sequence serial restart start with 1;
This feature was officially added in 18c but is unofficially available since 12.1.
It is arguably safe to use this undocumented feature in 12.1. Even though the syntax is not included in the official documentation, it is generated by the Oracle pa...
Compelling examples of custom C++ allocators?
What are some really good reasons to ditch std::allocator in favor of a custom solution? Have you run across any situations where it was absolutely necessary for correctness, performance, scalability, etc? Any really clever examples?
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