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初窥InnoDB的Memcached插件 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
...件所需要的配置信息：
mysql> USE innodb_memcache
mysql> SHOW TABLES;
+---------------------------+
| Tables_in_innodb_memcache |
+---------------------------+
| cache_policies |
| config_options |
| containers |
+---------------------------+
...
Is storing a delimited list in a database column really that bad?
...m in a comma separated list of values stored in one column of the database table.
10 Answers
...
Should I commit or rollback a read transaction?
...
Suppose I create a temp table, populate it with ids, join it with a data table to select the data that goes with the ids, then delete the temp table. I'm really just reading data, and I don't care what happens to the temp table, since it's temporar...
Match whitespace but not newlines
...Unicode, use code similar to the sub below to construct a pattern from the table in the aforementioned documentation section.
sub ws_not_nl {
local($_) = <<'EOTable';
0x0009 CHARACTER TABULATION h s
0x000a LINE FEED (LF) vs
0x000b LINE TABULATION vs ...
When to use ' (or quote) in Lisp?
...where you in other languages would have used strings, such as keys to hash tables.
This is where quote comes in. Say you want to plot resource allocations from a Python application, but rather do the plotting in Lisp. Have your Python app do something like this:
print("'(")
while allocating:
...
Aggregate / summarize multiple variables per group (e.g. sum, mean)
...
Using the data.table package, which is fast (useful for larger datasets)
https://github.com/Rdatatable/data.table/wiki
library(data.table)
df2 <- setDT(df1)[, lapply(.SD, sum), by=.(year, month), .SDcols=c("x1","x2")]
setDF(df2) # con...
SQL Server: Get table primary key using sql query [duplicate]
I want to get a particular table's primary key using SQL query for SQL Server database.
10 Answers
...
Cleanest way to build an SQL string in Java
...pared statements:
PreparedStatement stm = c.prepareStatement("UPDATE user_table SET name=? WHERE id=?");
stm.setString(1, "the name");
stm.setInt(2, 345);
stm.executeUpdate();
The other thing that can be done is to keep all queries in properties file. For example
in a queries.properties file can ...
Function to Calculate Median in SQL Server
... the 7 years since, but personally I wouldn't use this function on a large table until I verified its performance vs. other solutions.
ORIGINAL 2009 POST IS BELOW:
There are lots of ways to do this, with dramatically varying performance. Here's one particularly well-optimized solution, from Median...
How to convert numbers between hexadecimal and decimal
...on from hex to decimal number, you can use the approach with pre-populated table of hex-to-decimal values.
Here is the code that illustrates that idea. My performance tests showed that it can be 20%-40% faster than Convert.ToInt32(...):
class TableConvert
{
static sbyte[] unhex_table =
...