Ruby 如何确定复制的行数?
我正在运行Postgres DB,并使用ruby中的Ruby 如何确定复制的行数?,ruby,postgresql,pg,rowcount,postgresql-copy,Ruby,Postgresql,Pg,Rowcount,Postgresql Copy,我正在运行Postgres DB,并使用ruby中的COPY命令将数据加载到临时表中 它看起来像这样: @conn = PG.connect(dbname: 'load_test') res = @conn.async_exec <<-QUERY COPY tmp_inventory FROM '#{infile_location}' CSV HEADER DELIMITER '|' QUERY @conn=PG.connect(数据库名:“负载测试”) res=@conn.a
COPY
命令将数据加载到临时表中
它看起来像这样:
@conn = PG.connect(dbname: 'load_test')
res = @conn.async_exec <<-QUERY
COPY tmp_inventory FROM '#{infile_location}' CSV HEADER DELIMITER '|'
QUERY
@conn=PG.connect(数据库名:“负载测试”)
res=@conn.async_exec您可以在Postgres中执行此操作,也可以直接从Ruby中的Postgres接口获取:
使用Ruby
更具体地说是课堂
我不是Ruby专家,但研究文档,而且似乎方法cmd_tuples
只适用于INSERT | DELETE | UPDATE | MOVE | FETCH
还有常数PGRES\u COPY\u OUT
或PGRES\u COPY\u IN
(针对当前案例)。似乎:
返回查询的状态。状态值为以下值之一:
PGRES_EMPTY_QUERY
PGRES_COMMAND_OK
PGRES_TUPLES_OK
PGRES_COPY_OUT
PGRES_COPY_IN
PGRES_BAD_RESPONSE
PGRES_NONFATAL_ERROR
PGRES_FATAL_ERROR
PGRES_COPY_BOTH
因此,在您的示例中,您应该通过以下方式获得所需的值:
res.result_status
使用Postgres
您可以使用PL/pgSQL函数以编程方式访问COPY
处理的行数(需要9.2+版本):
埃尔文·布兰德施泰特走上了正确的道路。尽管Ruby API文档目前说(它需要更新),
PG::Result#cmd_tuples
至少在PostgreSQL 9.6.3中可以使用COPY
命令。当被问到这个问题时,它可能没有,但现在包含了COPY
,因此我将更新Ruby API的文档以反映这一点
这是的一个修改版本,它使用PG::Connection#copy_data
包装方法围绕libpq
的copy
API:
require 'pg'
require 'stringio'
$stderr.puts "Opening database connection ..."
conn = PG.connect( dbname: 'test' )
conn.exec( <<END_SQL )
DROP TABLE IF EXISTS logs;
CREATE TABLE logs (
client_ip inet,
username text,
ts timestamp,
request text,
status smallint,
bytes int
);
END_SQL
csv_io = StringIO.new( <<"END_DATA" )
"127.0.0.1","","30/Aug/2010:08:21:24 -0700","GET /manual/ HTTP/1.1",404,205
"127.0.0.1","","30/Aug/2010:08:21:24 -0700","GET /favicon.ico HTTP/1.1",404,209
"127.0.0.1","","30/Aug/2010:08:21:24 -0700","GET /favicon.ico HTTP/1.1",404,209
"127.0.0.1","","30/Aug/2010:08:22:29 -0700","GET /manual/ HTTP/1.1",200,11094
"127.0.0.1","","30/Aug/2010:08:22:38 -0700","GET /manual/index.html HTTP/1.1",200,725
"127.0.0.1","","30/Aug/2010:08:27:56 -0700","GET /manual/ HTTP/1.1",200,11094
"127.0.0.1","","30/Aug/2010:08:27:57 -0700","GET /manual/ HTTP/1.1",200,11094
"127.0.0.1","","30/Aug/2010:08:28:06 -0700","GET /manual/index.html HTTP/1.1",200,7709
"127.0.0.1","","30/Aug/2010:08:28:06 -0700","GET /manual/images/feather.gif HTTP/1.1",200,6471
"127.0.0.1","","30/Aug/2010:08:28:06 -0700","GET /manual/images/left.gif HTTP/1.1",200,60
"127.0.0.1","","30/Aug/2010:08:28:06 -0700","GET /manual/style/css/manual.css HTTP/1.1",200,18674
"127.0.0.1","","30/Aug/2010:08:28:06 -0700","GET /manual/style/css/manual-print.css HTTP/1.1",200,13200
"127.0.0.1","","30/Aug/2010:08:28:06 -0700","GET /manual/images/favicon.ico HTTP/1.1",200,1078
"127.0.0.1","","30/Aug/2010:08:28:06 -0700","GET /manual/style/css/manual-loose-100pc.css HTTP/1.1",200,3065
"127.0.0.1","","30/Aug/2010:08:28:14 -0700","OPTIONS * HTTP/1.0",200,0
"127.0.0.1","","30/Aug/2010:08:28:15 -0700","OPTIONS * HTTP/1.0",200,0
"127.0.0.1","","30/Aug/2010:08:28:47 -0700","GET /manual/mod/directives.html HTTP/1.1",200,33561
"127.0.0.1","","30/Aug/2010:08:28:53 -0700","GET /manual/mod/mpm_common.html HTTP/1.1",200,67683
"127.0.0.1","","30/Aug/2010:08:28:53 -0700","GET /manual/images/down.gif HTTP/1.1",200,56
"127.0.0.1","","30/Aug/2010:08:28:53 -0700","GET /manual/images/up.gif HTTP/1.1",200,57
"127.0.0.1","","30/Aug/2010:09:19:58 -0700","GET /manual/mod/mod_log_config.html HTTP/1.1",200,28307
"127.0.0.1","","30/Aug/2010:09:20:19 -0700","GET /manual/mod/core.html HTTP/1.1",200,194144
"127.0.0.1","","30/Aug/2010:16:02:56 -0700","GET /manual/ HTTP/1.1",200,11094
"127.0.0.1","","30/Aug/2010:16:03:00 -0700","GET /manual/ HTTP/1.1",200,11094
"127.0.0.1","","30/Aug/2010:16:06:16 -0700","GET /manual/mod/mod_dir.html HTTP/1.1",200,10583
"127.0.0.1","","30/Aug/2010:16:06:44 -0700","GET /manual/ HTTP/1.1",200,7709
END_DATA
### You can test the error case from the database side easily by
### changing one of the numbers at the end of one of the above rows to
### something non-numeric like "-".
$stderr.puts "Running COPY command with data ..."
buf = ''
conn.transaction do
res = conn.copy_data( "COPY logs FROM STDIN WITH csv" ) do
$stderr.print "Sending lines... "
csv_io.each_line.with_index do |buf, i|
$stderr.print "#{i + 1} "
conn.put_copy_data( buf )
end
$stderr.puts "done."
end
$stderr.puts "Result of COPY is: %s" % [ res.res_status(res.result_status) ]
$stderr.puts " tuples copied: %p" % [ res.cmd_tuples ]
end
conn.finish
PG::Result#Result_status
方法只返回一个整数结果状态代码,而PGRES_COPY_OUT
/PGRES_COPY_IN
被低级COPY
API使用,因此它们在正常情况下不是很有用。@Erwin Brandstetter:你能帮助我理解在Ruby上下文中如何做到这一点吗?如果我理解正确,链接的问题是关于PG CLI上的查询。我明白了。在Ruby上下文中执行它需要一种不同的方法。
$ ruby sample/copyfrom.rb
Opening database connection ...
Running COPY command with data ...
Sending lines... 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 done.
Result of COPY is: PGRES_COMMAND_OK
tuples copied: 26