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lua-resty-mysql - Lua MySQL client driver for ngx_lua based on the cosocket API

• Name
• Status
• Description
• Synopsis
• Methods
  • new
  • connect
  • set_timeout
  • set_keepalive
  • get_reused_times
  • close
  • send_query
  • read_result
  • query
  • server_ver
  • set_compact_arrays
• SQL Literal Quoting
• Multi-Resultset Support
• Debugging
• Automatic Error Logging
• Limitations
• More Authentication Method Support
• Installation
• Community
  • English Mailing List
  • Chinese Mailing List
• Bugs and Patches
• TODO
• Author
• Copyright and License
• See Also

This library is considered production ready.

This Lua library is a MySQL client driver for the ngx_lua nginx module:

https://github.com/openresty/lua-nginx-module

This Lua library takes advantage of ngx_lua's cosocket API, which ensures100% nonblocking behavior.

Note that at leastngx_lua 0.9.11 orngx_openresty 1.7.4.1 is required.

Also, thebit library is also required. If you're using LuaJIT 2 with ngx_lua, then thebit library is already available by default.

#youdonotneedthefollowinglineifyouareusing#thengx_openrestybundle:lua_package_path"/path/to/lua-resty-mysql/lib/?.lua;;";server {location/test {content_by_lua'localmysql=require"resty.mysql"localdb,err=mysql:new()ifnotdbthenngx.say("failed to instantiate mysql:",err)returnenddb:set_timeout(1000)-- 1 sec-- or connect to a unix domain socket file listened-- by a mysql server:--     local ok, err, errcode, sqlstate =--           db:connect{--              path = "/path/to/mysql.sock",--              database = "ngx_test",--              user = "ngx_test",--              password = "ngx_test" }localok,err,errcode,sqlstate=db:connect{host="127.0.0.1",port=3306,database="ngx_test",user="ngx_test",password="ngx_test",charset="utf8",max_packet_size=1024*1024,                }ifnotokthenngx.say("failed to connect:",err,":",errcode,"",sqlstate)db:close()returnendngx.say("connected to mysql.")localres,err,errcode,sqlstate=db:query("drop table if exists cats")ifnotresthenngx.say("bad result:",err,":",errcode,":",sqlstate,".")db:close()returnendres,err,errcode,sqlstate=db:query("create table cats".."(id serial primary key,".."name varchar(5))")ifnotresthenngx.say("bad result:",err,":",errcode,":",sqlstate,".")db:close()returnendngx.say("table cats created.")res,err,errcode,sqlstate=db:query("insert into cats (name)".."values (\'Bob\'),(\'\'),(null)")ifnotresthenngx.say("bad result:",err,":",errcode,":",sqlstate,".")db:close()returnendngx.say(res.affected_rows," rows inserted into table cats","(last insert id:",res.insert_id,")")-- run a select query, expected about 10 rows in-- the result set:res,err,errcode,sqlstate=db:query("select * from cats order by id asc",10)ifnotresthenngx.say("bad result:",err,":",errcode,":",sqlstate,".")db:close()returnendlocalcjson=require"cjson"ngx.say("result:",cjson.encode(res))-- put it into the connection pool of size 100,-- with 10 seconds max idle timeoutlocalok,err=db:set_keepalive(10000,100)ifnotokthenngx.say("failed to set keepalive:",err)db:close()returnend-- or just close the connection right away:-- local ok, err = db:close()-- if not ok then--     ngx.say("failed to close: ", err)--     return-- end';        }    }

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syntax: db, err = mysql:new()

Creates a MySQL connection object. In case of failures, returnsnil and a string describing the error.

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syntax: ok, err, errcode, sqlstate = db:connect(options)

Attempts to connect to the remote MySQL server.

Theoptions argument is a Lua table holding the following keys:

• host

  the host name for the MySQL server.

• port

  the port that the MySQL server is listening on. Default to 3306.

• path

  the path of the unix socket file listened by the MySQL server.

• database

  the MySQL database name.

• user

  MySQL account name for login.

• password

  MySQL account password for login (in clear text).

• charset

  the character set used on the MySQL connection, which can be different from the default charset setting.The following values are accepted:big5,dec8,cp850,hp8,koi8r,latin1,latin2,swe7,ascii,ujis,sjis,hebrew,tis620,euckr,koi8u,gb2312,greek,cp1250,gbk,latin5,armscii8,utf8,ucs2,cp866,keybcs2,macce,macroman,cp852,latin7,utf8mb4,cp1251,utf16,utf16le,cp1256,cp1257,utf32,binary,geostd8,cp932,eucjpms,gb18030.

• max_packet_size

  the upper limit for the reply packets sent from the MySQL server (default to 1MB).

• ssl

  If set totrue, then uses SSL to connect to MySQL (default tofalse). If the MySQLserver does not have SSL support(or just disabled), the error string "ssl disabled on server" will be returned.

• ssl_verify

  If set totrue, then verifies the validity of the server SSL certificate (default tofalse).Note that you need to configure thelua_ssl_trusted_certificateto specify the CA (or server) certificate used by your MySQL server. You may alsoneed to configurelua_ssl_verify_depthaccordingly.

• pool

  the name for the MySQL connection pool. if omitted, an ambiguous pool name will be generated automatically with the string templateuser:database:host:port oruser:database:path. (this option was first introduced inv0.08.)

• pool_size

  Specifies the size of the connection pool. If omitted and nobacklog option was provided, no pool will be created. If omitted butbacklog was provided, the pool will be created with a default size equal to the value of thelua_socket_pool_size directive. The connection pool holds up topool_size alive connections ready to be reused by subsequent calls toconnect, but note that there is no upper limit to the total number of opened connections outside of the pool. If you need to restrict the total number of opened connections, specify thebacklog option. When the connection pool would exceed its size limit, the least recently used (kept-alive) connection already in the pool will be closed to make room for the current connection. Note that the cosocket connection pool is per Nginx worker process rather than per Nginx server instance, so the size limit specified here also applies to every single Nginx worker process. Also note that the size of the connection pool cannot be changed once it has been created. Note that at leastngx_lua 0.10.14 is required to use this options.

• backlog

  If specified, this module will limit the total number of opened connections for this pool. No more connections thanpool_size can be opened for this pool at any time. If the connection pool is full, subsequent connect operations will be queued into a queue equal to this option's value (the "backlog" queue). If the number of queued connect operations is equal tobacklog, subsequent connect operations will fail and return nil plus the error string"too many waiting connect operations". The queued connect operations will be resumed once the number of connections in the pool is less thanpool_size. The queued connect operation will abort once they have been queued for more thanconnect_timeout, controlled byset_timeout, and will return nil plus the error string "timeout". Note that at leastngx_lua 0.10.14 is required to use this options.

• compact_arrays

  when this option is set to true, then thequery andread_result methods will return the array-of-arrays structure for the resultset, rather than the default array-of-hashes structure.

Before actually resolving the host name and connecting to the remote backend, this method will always look up the connection pool for matched idle connections created by previous calls of this method.

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syntax: db:set_timeout(time)

Sets the timeout (in ms) protection for subsequent operations, including theconnect method.

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syntax: ok, err = db:set_keepalive(max_idle_timeout, pool_size)

Puts the current MySQL connection immediately into the ngx_lua cosocket connection pool.

You can specify the max idle timeout (in ms) when the connection is in the pool and the maximal size of the pool every nginx worker process.

In case of success, returns1. In case of errors, returnsnil with a string describing the error.

Only call this method in the place you would have called theclose method instead. Calling this method will immediately turn the currentresty.mysql object into theclosed state. Any subsequent operations other thanconnect() on the current objet will return theclosed error.

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syntax: times, err = db:get_reused_times()

This method returns the (successfully) reused times for the current connection. In case of error, it returnsnil and a string describing the error.

If the current connection does not come from the built-in connection pool, then this method always returns0, that is, the connection has never been reused (yet). If the connection comes from the connection pool, then the return value is always non-zero. So this method can also be used to determine if the current connection comes from the pool.

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syntax: ok, err = db:close()

Closes the current mysql connection and returns the status.

In case of success, returns1. In case of errors, returnsnil with a string describing the error.

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syntax: bytes, err = db:send_query(query)

Sends the query to the remote MySQL server without waiting for its replies.

Returns the bytes successfully sent out in success and otherwise returnsnil and a string describing the error.

You should use theread_result method to read the MySQL replies afterwards.

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syntax: res, err, errcode, sqlstate = db:read_result()

syntax: res, err, errcode, sqlstate = db:read_result(nrows)

Reads in one result returned from the MySQL server.

It returns a Lua table (res) describing the MySQLOK packet orresult set packet for the query result.

For queries corresponding to a result set, it returns an array holding all the rows. Each row holds key-value pairs for each data fields. For instance,

    {        {name="Bob",age=32,phone=ngx.null },        {name="Marry",age=18,phone="10666372"}    }

For queries that do not correspond to a result set, it returns a Lua table like this:

    {insert_id=0,server_status=2,warning_count=1,affected_rows=32,message=nil    }

If more results are following the current result, a seconderr return value will be given the stringagain. One should always check this (second) return value and if it isagain, then she should call this method again to retrieve more results. This usually happens when the original query contains multiple statements (separated by semicolon in the same query string) or calling a MySQL procedure. See alsoMulti-Resultset Support.

In case of errors, this method returns at most 4 values:nil,err,errcode, andsqlstate. Theerr return value contains a string describing the error, theerrcode return value holds the MySQL error code (a numerical value), and finally, thesqlstate return value contains the standard SQL error code that consists of 5 characters. Note that, theerrcode andsqlstate might benil if MySQL does not return them.

The optional argumentnrows can be used to specify an approximate number of rows for the result set. This value can be usedto pre-allocate space in the resulting Lua table for the result set. By default, it takes the value 4.

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syntax: res, err, errcode, sqlstate = db:query(query)

syntax: res, err, errcode, sqlstate = db:query(query, nrows)

This is a shortcut for combining thesend_query call and the firstread_result call.

You should always check if theerr return value isagain in case of success because this method will only callread_result only once for you. See alsoMulti-Resultset Support.

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syntax: str = db:server_ver()

Returns the MySQL server version string, like"5.1.64".

You should only call this method after successfully connecting to a MySQL server, otherwisenil will be returned.

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syntax: db:set_compact_arrays(boolean)

Sets whether to use the "compact-arrays" structure for the resultsets returned by subsequent queries. See thecompact_arrays option for theconnect method for more details.

This method was first introduced in thev0.09 release.

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It is always important to quote SQL literals properly to prevent SQL injection attacks. You can use thengx.quote_sql_str function provided by ngx_lua to quote values.Here is an example:

localname=ngx.unescape_uri(ngx.var.arg_name)localquoted_name=ngx.quote_sql_str(name)localsql="select * from users where name ="..quoted_name

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For a SQL query that produces multiple result-sets, it is always your duty to check the "again" error message returned by thequery orread_result method calls, and keep pulling more result sets by calling theread_result method until no "again" error message returned (or some other errors happen).

Below is a trivial example for this:

localcjson=require"cjson"localmysql=require"resty.mysql"localdb=mysql:new()localok,err,errcode,sqlstate=db:connect({host="127.0.0.1",port=3306,database="world",user="monty",password="pass"})ifnotokthenngx.log(ngx.ERR,"failed to connect:",err,":",errcode,"",sqlstate)returnngx.exit(500)endres,err,errcode,sqlstate=db:query("select 1; select 2; select 3;")ifnotresthenngx.log(ngx.ERR,"bad result #1:",err,":",errcode,":",sqlstate,".")db:close()returnngx.exit(500)endngx.say("result #1:",cjson.encode(res))locali=2whileerr=="again"dores,err,errcode,sqlstate=db:read_result()ifnotresthenngx.log(ngx.ERR,"bad result #",i,":",err,":",errcode,":",sqlstate,".")db:close()returnngx.exit(500)endngx.say("result #",i,":",cjson.encode(res))i=i+1endlocalok,err=db:set_keepalive(10000,50)ifnotokthenngx.log(ngx.ERR,"failed to set keepalive:",err)db:close()ngx.exit(500)end

This code snippet will produce the following response body data:

result #1: [{"1":"1"}]result #2: [{"2":"2"}]result #3: [{"3":"3"}]

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It is usually convenient to use thelua-cjson library to encode the return values of the MySQL query methods to JSON. For example,

localcjson=require"cjson"...localres,err,errcode,sqlstate=db:query("select * from cats")ifresthenprint("res:",cjson.encode(res))end

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By default the underlyingngx_lua moduledoes error logging when socket errors happen. If you are already doing proper errorhandling in your own Lua code, then you are recommended to disable this automatic error logging by turning offngx_lua'slua_socket_log_errors directive, that is,

    lua_socket_log_errors off;

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• This library cannot be used in code contexts like init_by_lua*, set_by_lua*, log_by_lua*, andheader_filter_by_lua* where the ngx_lua cosocket API is not available.
• Theresty.mysql object instance cannot be stored in a Lua variable at the Lua module level,because it will then be shared by all the concurrent requests handled by the same nginxworker process (seehttps://github.com/openresty/lua-nginx-module#data-sharing-within-an-nginx-worker ) andresult in bad race conditions when concurrent requests are trying to use the sameresty.mysql instance.You should always initiateresty.mysql objects in function localvariables or in thengx.ctx table. These places all have their own data copies foreach request.

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By default, Of all authentication method, onlyOld Password Authentication(mysql_old_password) andSecure Password Authentication(mysql_native_password) are suppored. If the server requiressha256_password or cache_sha2_password, an error likeauth plugin caching_sha2_password or sha256_password are not supported because resty.rsa is not installed may be returned.

Needlua-resty-rsa when using thesha256_password andcache_sha2_password.

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If you are using the ngx_openresty bundle (http://openresty.org ), thenyou do not need to do anything because it already includes and enableslua-resty-mysql by default. And you can just use it in your Lua code,as in

localmysql=require"resty.mysql"...

If you are using your own nginx + ngx_lua build, then you need to configurethe lua_package_path directive to add the path of your lua-resty-mysql sourcetree to ngx_lua's LUA_PATH search path, as in

    # nginx.confhttp{        lua_package_path"/path/to/lua-resty-mysql/lib/?.lua;;";        ...}

Ensure that the system account running your Nginx ''worker'' proceses haveenough permission to read the.lua file.

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Theopenresty-en mailing list is for English speakers.

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Theopenresty mailing list is for Chinese speakers.

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Please submit bug reports, wishlists, or patches by

1. creating a ticket on theGitHub Issue Tracker,
2. or posting to theOpenResty community.

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• improve the MySQL connection pool support.
• implement the MySQL binary row data packets.
• implement MySQL server prepare and execute packets.
• implement the data compression support in the protocol.

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Yichun "agentzh" Zhang (章亦春)agentzh@gmail.com, OpenResty Inc.

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This module is licensed under the BSD license.

Copyright (C) 2012-2018, by Yichun "agentzh" Zhang (章亦春)agentzh@gmail.com, OpenResty Inc.

All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

• Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

• Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

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• the ngx_lua module:https://github.com/openresty/lua-nginx-module
• the MySQL wired protocol specification:http://forge.mysql.com/wiki/MySQL_Internals_ClientServer_Protocol
• thelua-resty-memcached library
• thelua-resty-redis library
• the ngx_drizzle module:https://github.com/openresty/drizzle-nginx-module

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