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Re: the status of filesystem storage engine in drizzle

 

This is very cool!

Is this pushed anywhere and/or proposed for merge yet?

On 07/11/2010 09:49 AM, ZQ wrote:
> http://www.dazuiniu.com/blog/2010/07/11/the-status-of-filesystem-storage-engine-in-drizzle.html
> 
> The file system storage engine is in shape now.
> 
> There are lots of storage engines in Drizzle already.  What’s this new
> storage engine used for?  To give you a rough idea, you can use the
> below SQL statement to read the file ‘/proc/loadavg’ directly.
> 
> drizzle> CREATE TABLE LoadAverage (
> load1 DECIMAL(3, 2),
> load5 DECIMAL(3, 2),
> load15 DECIMAL(3, 2),
> active_processes VARCHAR(12),
> lastpid INTEGER) ENGINE=FILESYSTEM, FILE="/proc/loadavg";
> 
> 
> drizzle> select * from LoadAverage;
> +-------+-------+--------+------------------+---------+
> | load1 | load5 | load15 | active_processes | lastpid |
> +-------+-------+--------+------------------+---------+
> 
> |  0.00 |  0.00 |   0.00 | 1/97             |    6061 |
> +-------+-------+--------+------------------+---------+
> 
> The file system storage engine eases our manipulation on disk file,
> especially those file under /proc directory.  This engine tries to be
> small and useful, like the calculator at your hand.
> 
> There are several options available for this storage engine for now. 
> Extra options provides extra functionalities.
> 
>    1. *FILE*.  This option specifies which file composes the
>       corresponding table.  This is the most important and useful
>       option, it’s a MUST option for this storage engine.
>    2. *ROW_SEPARATOR*.  This option specifies which characters should be
>       taken as end-of-line.  The default is “\n”.
>    3. *COL_SEPARATOR*.  This option specifies which characters should be
>       taken as the delimiter for columns.  The default is ” \t” (space
>       and tab), it’s reasonable to make it as default.
>    4. *SEPARATOR_MODE*.  It has three values, STRICT, GENERAL, WEAK. 
>       This one is a little tricky to understand. It shows the rule how
>       to treat continuous separators. For example, if we have the line
>       “111<SPACE><SPACE><SPACE>222″, the columns in WEAK mode would be
>       only two columns “111″ and “222″; the columns in other modes would
>       be four columns “111″, NULL, NULL, “222″. GENERAL mode will omit
>       empty lines in the file; while STRICT mode will ruthlessly add an
>       entire empty tuple into this table.
>    5. *FORMAT*. This is a newly added feature.  It’s written to process
>       the file “/proc/meminfo”. This file has the similar format as key
>       and value each line. What about we transpose these columns and
>       rows and make all these keys as the column in a table? That should
>       be cool. Yes, we can do this. Specify “KEY_VALUE” as the value of
>       this option and set the FILE to ‘/proc/meminfo’, here you go:
> 
>       CREATE TABLE t1 (a int) ENGINE=FILESYSTEM,FILE="/proc/meminfo",FORMAT="KEY_VALUE",COL_SEPARATOR=": ";
>       SELECT * FROM t1;
>       Active  AnonPages       Bounce  Buffers Cached  CommitLimit     Committed_AS    DirectMap2M     DirectMap4k     Dirty   HugePages_Free  HugePages_Rsvd  HugePages_Surp  HugePages_Total Hugepagesize    InactiveMapped  MemFree MemTotal        NFS_Unstable    PageTables      SReclaimable    SUnreclaim      Slab   SwapCached       SwapFree        SwapTotal       VmallocChunk    VmallocTotal    VmallocUsed     Writeback       WritebackTmp
> 
>       1526364 198768  0       221004  2829356 2600136 495728  4186112 7040    1916    0       0       0      02048    1722772 51064   502844  4059680 0       27124   198000  12076   210076  0       570296  570296 34359655499      34359738367     82808   0       0
> 
>       SHOW CREATE TABLE t1;
>       Table   Create Table
>       t1      CREATE TABLE `t1` (
>       `Active` varchar(8) DEFAULT NULL,
>       `AnonPages` varchar(7) DEFAULT NULL,
>       ...some lines omitted...
>       `Writeback` varchar(2) DEFAULT NULL,
> 
>       `WritebackTmp` varchar(2) DEFAULT NULL
>       ) ENGINE=FILESYSTEM FILE='/proc/meminfo' FORMAT='KEY_VALUE' COL_SEPARATOR=': '
> 
> There are still some TODOs on my list:
> 
>    1. enclosing and quotation is not there.
>    2. more test cases to cover some corner cases.
>    3. …
> 
> I would like my project to be useful, and I encourage all DBAs,
> administrators to give a try and see whether it fits your daily use. 
> Any feedback is welcome! :-)
> 
> 
> 
> --Zimin
> 
> 
> 
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