Sql Server, Temporary Tables With Truncate Vs Table Variable With Delete

I have a stored procedure inside which I create a temporary table that typically contains between 1 and 10 rows. This table is truncated and filled many times during the stored pro

Solution 1:

Running the followign to scripts, it would seem that the Table Variable is the better option

CREATETABLE #Temp(
        ID INT
)

DECLARE@IntINT,
        @InnerIntINTSELECT@Int=1,
        @InnerInt=1

WHILE @Int<50000BEGIN
    WHILE @InnerInt<10BEGININSERTINTO #Temp SELECT@InnerIntSET@InnerInt=@InnerInt+1ENDSELECT@Int=@Int+1,
            @InnerInt=1TRUNCATETABLE #Temp
ENDDROPTABLE #TEMP

GO

DECLARE@TempTABLE(
        ID INT
)

DECLARE@IntINT,
        @InnerIntINTSELECT@Int=1,
        @InnerInt=1

WHILE @Int<50000BEGIN
    WHILE @InnerInt<10BEGININSERTINTO@TempSELECT@InnerIntSET@InnerInt=@InnerInt+1ENDSELECT@Int=@Int+1,
            @InnerInt=1DELETEFROM@TempEND

From Sql Profiler

CPU     Reads   Writes  Duration
363752799937039319

vs

CPU     Reads   Writes  Duration
147501700031217376

Solution 2:

Quite frankly, with only 10 or 20 (or even 100) entries, any difference in speed would be in a sub-nanosecond realm. Forget about it - don't even waste a second of your brain time on this - it's a non-issue!

In general

• table variables will be kept in memory up a certain size - if they go beyond that, they're swapped out to disk in the tempdb database, too - just like temporary tables. Plus: if a temporary table has only a handful of entries, they'll most like be stored on a single 8k page anyway, and as soon as you access one of the entries, that entire page (and thus the whole temporary table) will be in SQL Server memory - so even here, there's really not a whole lot of benefits to table variables...

• table variables don't support indices nor statistics, which means if you have more than a handful of entries, and especially if you need to search and query this "entity", you're better off with a temporary table

So all in all : I personally use temporary tables more often than table variables, especially if I have more than 10 entries or something like that. Being able to index the temp table, and having statistics on it, usually pays off big time compared to any potential gain a table variable might have, performance-wise.