RE: Why read row is so slower than read column.
Hi, I would recommend to turn tracing on in CQL. Using this you can find out that part of the query results in high latency. http://www.datastax.com/documentation/cql/3.0/cql/cql_reference/tracing_r.html Regards Andi From: yhq...@sina.com [yhq...@sina.com] Sent: 26 December 2014 14:01 To: user Subject: Why read row is so slower than read column. Hi, all: In my cf, each row has two column, one column is the timestamp(64bit), another column is data which may be 500k about. I read row, the qps is about 30. I read that data column, the qps is about 500. Why read performance is so slow where add a so small column in read?? Thanks.
Re: Re: Why read row is so slower than read column.
Can you send us your exact data model? Even though you normally use Thrift, you may also be able to access the data from CQL, and if so, query tracing is a very powerful feature in CQL which may describe why there is a performance difference. Do you do deletes of data? If so, tombstones really may be the cause of the performance difference. On Fri, Dec 26, 2014 at 6:58 PM, yhq...@sina.com wrote: I use thrift interface to query the data. - - What do your CQL queries look like? -- Jack Krupansky On Fri, Dec 26, 2014 at 8:00 AM, yhq...@sina.com wrote: Hi, all: In my cf, each row has two column, one column is the timestamp(64bit), another column is data which may be 500k about. I read row, the qps is about 30. I read that data column, the qps is about 500. Why read performance is so slow where add a so small column in read?? Thanks.
Why read row is so slower than read column.
Hi, all: In my cf, each row has two column, one column is the timestamp(64bit), another column is data which may be 500k about. I read row, the qps is about 30. I read that data column, the qps is about 500. Why read performance is so slow where add a so small column in read?? Thanks.
Why read row is so slower than read column.
Hi, all: In my cf, each row has two column, one column is the timestamp(64bit), another column is data which may be 500k about. I read row, the qps is about 30. I read that data column, the qps is about 500. Why read performance is so slow where add a so small column in read?? Thanks.
Re: Why read row is so slower than read column.
What do your CQL queries look like? -- Jack Krupansky On Fri, Dec 26, 2014 at 8:00 AM, yhq...@sina.com wrote: Hi, all: In my cf, each row has two column, one column is the timestamp(64bit), another column is data which may be 500k about. I read row, the qps is about 30. I read that data column, the qps is about 500. Why read performance is so slow where add a so small column in read?? Thanks.
Re: Why read row is so slower than read column.
I would suggest enabling tracing in cqlsh and see what it has to say. There are many things which could cause this, but I'm thinking in particular you may have a lot of tombstones which get lifted when you read the whole row, and are missed when you read just one column. On Fri, Dec 26, 2014 at 6:05 AM, Jack Krupansky jack.krupan...@gmail.com wrote: What do your CQL queries look like? -- Jack Krupansky On Fri, Dec 26, 2014 at 8:00 AM, yhq...@sina.com wrote: Hi, all: In my cf, each row has two column, one column is the timestamp(64bit), another column is data which may be 500k about. I read row, the qps is about 30. I read that data column, the qps is about 500. Why read performance is so slow where add a so small column in read?? Thanks.
转发：Re: Why read row is so slower than read column.
I use thrift interface to query the data. - - What do your CQL queries look like?-- Jack Krupansky On Fri, Dec 26, 2014 at 8:00 AM, yhq...@sina.com wrote: Hi, all: In my cf, each row has two column, one column is the timestamp(64bit), another column is data which may be 500k about. I read row, the qps is about 30. I read that data column, the qps is about 500. Why read performance is so slow where add a so small column in read?? Thanks.
