Updating two tables in sql
Soon you will be able to automatically create and update statistics on single columns and indexes.
By using the following information, you can greatly automate the management of the statistics on your data.
This is because the SQL Data Warehouse query optimizer is a cost-based optimizer.
It compares the cost of various query plans, and then chooses the plan with the lowest cost, which is in most cases the plan that executes the fastest.
However, updating statistics on all columns as your data grows can consume memory.
The following are recommendations for different scenarios: One best practice is to update statistics on date columns each day as new dates are added.
" This question is not one that can be answered by the age of the data.
An up-to-date statistics object might be old if there's been no material change to the underlying data.
SELECT sm.[name] AS [schema_name], tb.[name] AS [table_name], co.[name] AS [stats_column_name], st.[name] AS [stats_name], STATS_DATE(st.[object_id],st.[stats_id]) AS [stats_last_updated_date] FROM sys.objects ob JOIN sys.stats st ON ob.[object_id] = st.[object_id] JOIN sys.stats_columns sc ON st.[stats_id] = sc.[stats_id] AND st.[object_id] = sc.[object_id] JOIN sys.columns co ON sc.[column_id] = co.[column_id] AND sc.[object_id] = co.[object_id] JOIN sys.types ty ON co.[user_type_id] = ty.[user_type_id] JOIN sys.tables tb ON co.[object_id] = tb.[object_id] JOIN sys.schemas sm ON tb.[schema_id] = sm.[schema_id] WHERE st.[user_created] = 1; Date columns in a data warehouse, for example, usually need frequent statistics updates.
However, if your data warehouse only contains one country and you bring in data from a new country, resulting in data from multiple countries being stored, then you need to update statistics on the country column.
One of the first questions to ask when you're troubleshooting a query is, "Are the statistics up to date?
The data load is when tables most frequently change their size and/or their distribution of values.
Therefore, this is a logical place to implement some management processes.