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I am loading data from a CSV file into a temp staging table and this temp table is being queried a lot. I looked at my execution plan and saw that a lot of the time is spent scanning the temp table.
Is there any way to create index on this table when I SELECT INTO it?
SELECT *
FROM TradeTable.staging.Security s
WHERE (
s.Identifier IS NOT NULL
OR s.ConstituentTicker IS NOT NULL
OR s.CompositeTicker IS NOT NULL
OR s.CUSIP IS NOT NULL
OR s.ISIN IS NOT NULL
OR s.SEDOL IS NOT NULL
OR s.eSignalTicker IS NOT NULL)
713
You can define indexes on temporary tables. In many cases, these indexes can improve the performance of queries that use tempdb. The optimizer uses these indexes just like indexes on ordinary user tables.
Adding indexes to the SQL temp tables will enhance its performance if the index is chosen correctly, otherwise, it can cause performance degradation.
We can use the SELECT INTO TEMP TABLE statement to perform the above tasks in one statement for the temporary tables. In this way, we can copy the source table data into the temporary tables in a quick manner.
SQL Server CREATE INDEX statement In this syntax: First, specify the name of the index after the CREATE NONCLUSTERED INDEX clause. Note that the NONCLUSTERED keyword is optional. Second, specify the table name on which you want to create the index and a list of columns of that table as the index key columns.
The table created by SELECT INTO is always a heap. If you want a PK/Identity column you can either do as you suggest in the comments
CREATE TABLE #T
(
Id INT IDENTITY(1,1) PRIMARY KEY,
/*Other Columns*/
)
INSERT INTO #T
SELECT *
FROM TradeTable.staging.Security
Or avoid the explicit CREATE and need to list all columns out with
SELECT TOP (0) IDENTITY(int,1,1) As Id, *
INTO #T
FROM TradeTable.staging.Security
ALTER TABLE #T ADD PRIMARY KEY(Id)
INSERT INTO #T
SELECT *
FROM TradeTable.staging.Security
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