The tag has no usage guidance.

learn more… | top users | synonyms

11
votes
1answer
188 views

stats_column_id and index_column_id do not update with physical order of clustered index is changed

Unless I'm misunderstanding the purpose of the column, the following code indicates that a change of the structure of the clustered index does not change the ordinal position (stats_column_id)of the ...
2
votes
1answer
567 views

Oracle 11g bug ? not returning the record until I triggered index to invisible and then to visible

We are using Oracle 11g, 11.2.0.3. We know a record exists in a table but a select is not returning it for some odd reason. The execution plans the general query, not forcing any index, shows that ...
0
votes
1answer
26 views

Data impact on analyzing mysql table stats

I have a MySQL database that appears to be getting slower over time. After some googling, I determine that the database probably needs to be analyzed. This is because innodb_stats_on_metadata is set ...
0
votes
1answer
523 views

How to organize the tables of a MySQL database with several statistics data of several years?

I am developing an app that must provide statistics information about the distribution of the money that a person spends each year in taxes in the city where he lives. The user should select the ...
0
votes
1answer
222 views

How to configure postgresql-9.2 to know blk_write_time in pg_stat_database

Interested in the procedure for collecting block write statistics of PostgreSQL 9.2. Steps followed for configuration, could get blk_read time but not blk_write_time CREATE EXTENSION adminpack; and ...
7
votes
0answers
127 views

How to do Statistics in Partial Indexes of PostgreSQL efficiently?

This answer motivated think again my following tables but I am still uncertain how to store variables/results from data analysis for quick selection in post-processing. If stored, I think it is well ...
3
votes
0answers
672 views

Do OR conditions in Oracle SQL queries spoil index use / cause full table scan?

I have a query on Oracle 11g of the following type, which results in a series of highly inefficient full table scans: select t.Id, t.ObjectId, t...[other Tasks columns] , od1...[ObjectData1 ...
2
votes
0answers
181 views

Oracle: separate column histograms for partitions

I have a partitioned table like MY_TABLE(PART_KEY, DATE_KEY, ...) with a local partitioned index on (PART_KEY, DATE_KEY). When I collect stats on the table, I end up with a HEIGHT BALANCED histogram ...
1
vote
0answers
44 views

Oracle tuning strategy for columns with long tails

We have an Oracle 11g database, where the two biggest tables are Customer and Order. The order profile of our customers has a long tail: we have millions of customers, with most only having a small ...
1
vote
0answers
87 views

Why wouldn't statistics update if all rows in a table were replaced?

We have several "reporting" tables in a SQL Server 2012 SP1 instance. Every hour, a job runs procedures that delete all the rows from these tables and then insert current data (involving lots of ...
1
vote
0answers
263 views

How to check what stats were used in query

respected DBAs . . . is it possible to tell when statistics were last accessed by a query using T-SQL? I'm trying to ascertain what statistics are involved in a query, I know I can check the visual ...
0
votes
0answers
38 views

Large differences between estimated and actual row counts but stats are OK

I'm having a problem with a Function which is taking 10 times longer to run than it used to and high CPU usage. And I'm puzzled by what I'm seeing in the execution plan with some index seek operators ...
0
votes
0answers
33 views

Generate N x M random sample table from normal distribution in MySQL

Is there an easy way to produce a table of, say 10000 (rows) by 500 (columns) of numbers from normal distribution with parameters mu = 1, std.dev = 5 ?
0
votes
0answers
52 views

Is it good to gather stats in Oracle?

I have a very new database, and I have a request to gather stats for some schemas.. is it okay to gather stats without any transactions processed in the database? What are the impacts it could have if ...
0
votes
0answers
61 views

Columnstore Index Scan Cardinality Estimates

In SQL Server 2012, I am seeing large cardinality estimate discrepancies for a columnstore index scan. It looks like statistics have been generated for the index, but I don't see any details in DBCC ...
0
votes
0answers
94 views

Sleeping queries blocking rebuild index and update statistics job in Always on

At one of your client sides we have configured Always on with synchronous mode.Also we have schedule rebuild index and update statistics job which runs in night every alternate day. the issue is ...
0
votes
0answers
158 views

Replicating Excel's CHIDIST function in Oracle 11g

I'm attempting to replicate the functionality of an Excel workbook in Oracle. One of the formulae on the worksheet uses CHIDIST, which "Returns the one-tailed probability of the chi-squared ...