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When to use Hadoop, HBase, Hive and Pig?
...ru some SQL like language
To replace daily aggregation data generated thru MySQL with Hive
Build Custom reports thru queries in Hive
Architecture Options
I benchmarked the following options:
Hive+HDFS
Hive+HBase - queries were too slow so I dumped this option
Design
Daily log Files were tr...
Can PHP PDO Statements accept the table or column name as parameter?
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I miss mysql_real_escape_string(). Maybe here I can say it without someone jumping in and saying "But you don't need it with PDO"
– Rolf
Oct 20 '18 at 8:39
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Convert from MySQL datetime to another format with PHP
I have a datetime column in MySQL.
18 Answers
18
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Linux 进程卡住了怎么办？ - 操作系统(内核) - 清泛网 - 专注C/C++及内核技术
...ffffffff>] 0xffffffffffffffff
这时候按 Ctrl+C 也不能退出。
root@localhost:~# ls /jfs
^C
^C^C^C^C^C
但是用 strace 却能唤醒它，并且开始处理之前的中断信号，然后就退出了。
root@localhost:~# strace -p `pgrep ls`
strace: Process 26469 attached
--- SI...
MySQL select one column DISTINCT, with corresponding other columns
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@Full Decent you can't, according to MySQL documentation: "The server is free to choose any value from each group, so unless they are the same, the values chosen are indeterminate.". In practice I've successfully used this kind of queries with ORDER BY clause, ...
MySQL: Large VARCHAR vs. TEXT?
I've got a messages table in MySQL which records messages between users. Apart from the typical ids and message types (all integer types) I need to save the actual message text as either VARCHAR or TEXT. I'm setting a front-end limit of 3000 characters which means the messages would never be inserte...
MySQL Conditional Insert
...his, dual is a table with one row only (found originally in Oracle, now in mysql too). The logic is that the SELECT statement generates a single row of data with the required values, but only when the values are not already found.
Alternatively, look at the MERGE statement.
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difference between primary key and unique key
I'm using mysql database. I have a confusion between primary key and unique key.
15 Answers
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MySQL and GROUP_CONCAT() maximum length
I'm using GROUP_CONCAT() in a MySQL query to convert multiple rows into a single string.
However, the maximum length of the result of this function is 1024 characters.
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Does MySQL index foreign key columns automatically?
Does MySQL index foreign key columns automatically?
9 Answers
9
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