1. # vs @ - it’s not about social media it’s about temporary tables and data
=tg= Thomas Grohser, NTT Data
SQL Server MVP
SQL Server Performance Engineering
Pittsburgh, PA 9/30/2017

2. select * from =tg= where topic =
Remark
SQL 4.21
First SQL Server ever used (1994)
SQL 6.0
First Log Shipping with failover
SQL 6.5
First SQL Server Cluster (NT4.0 + Wolfpack)
SQL 7.0
2+ billion rows / month in a single Table
SQL 2000
938 days with 100% availability
SQL 2000 IA64
First SQL Server on Itanium IA64
SQL 2005 IA64
First OLTP long distance database mirroring
SQL 2008 IA64
First Replication into mirrored databases
SQL 2008R2 IA64
SQL 2008R2 x64
First 256 CPUs & > STMT/sec
First Scale out > STMT/sec
First time 1.2+ trillion rows in a table
SQL 2012
> Transactions per second
> 1.3 Trillion Rows in a table
SQL 2014
> Transactions per second
Fully automated deploy and management
SQL 2016
AlwaysOn Automatic HA and DR, crossed the PB in storage
SQL vNext
Can’t wait to push the limits even further
=tg= Thomas Grohser,
NTT DATA
Senior Director Technical Solutions Architecture /
Focus on SQL Server Security, Performance Engineering,
Infrastructure and Architecture
Wrote some of
Close Relationship with
SQLCAT (SQL Server Customer Advisory Team)
SCAN (SQL Server Customer Advisory Network)
TAP (Technology Adoption Program)
Product Teams in Redmond
Active PASS member and
PASS Summit Speaker
23 Years with SQL Server

3. What is the difference between @ and #?29
SELECT - ASCII('#')

4. Source Temporary Target
Repeatable

5. How to measure performance
Time to read source(s) n x sources
Time to create temp table 1 x
Time to insert into temp table n x sources
Time to modify temp table 1 x
Time to read temp table n x targets
Time to insert into target(s) n x targets

6. Options for Temporary Tables
AS TABLE (…); @Table
CREATE #TableName (…); #Table
CREATE ##TableName (…); ##Table
Use TempDB; CREATE TableName (…); TinTDB
CREATE TABLE TableName ( … ) WITH ( MO
MEMORY_OPTIMIZED=ON,
DURABILITY=SCHEMA_ONLY);
CREATE TABLE TableName ( … ) WITH ( MOD
DURABILITY=SCHEMA_AND_DATA);
Use MyDatabase; CREATE TABLE … UT

7. Indexes @Table Yes during declaration only
DEMO
@Table Yes during declaration only
#Table Yes (Clustered, Non Clustered, Filtered)
##Table Yes (Clustered, Non Clustered, Filtered)
TinTDB Yes (Clustered, Non Clustered, Filtered)
MO Yes (Hash and BTree)
MOD Yes (Hash and BTree)
UT Yes (Clustered, Non Clustered, Filtered, Special)

8. Scope / Isolation / Durability
@Table Current Batch Yes None
#Table Current Session Yes None
##Table Global No None
TinTDB Global No None
MO Global No None
MOD Global No Yes
UT Global No Yes
DEMO

9. Create Table Triggers Recompilation
@Table No
#Table Yes
##Table Yes
TinTDB Yes
MO Yes
MOD Yes
UT Yes

10. Statistics @Table No #Table Yes ##Table Yes TinTDB Yes MO Yes MOD Yes
UT Yes
Cardinality is assumed to be 30% of row count
Same problems as with normal tables that update statistics might not be triggered depending on number of rows added/changed
Manual Update Statistics can happen

11. Commit / Rollback supported
@Table Yes No
#Table Yes Yes
##Table Yes Yes
TinTDB Yes Yes
MO Yes Yes
MOD Yes Yes
UT Yes Yes
DEMO

12. Truncate table @Table No #Table Yes ##Table Yes TinTDB Yes
MO No (but DELETE is super fast)
MOD No (but DELETE is super fast)
UT Yes

13. Transaction Log IO @Table None #Table Reduced (no recovery needed)
TinTDB Reduced (no recovery needed)
MO None
MOD Optimized
UT Yes
TempDB
Your DB

14. Locking and Blocking @Table No #Table No ##Table Yes TinTDB Yes
MO No (retry logic for updates/deletes)
MOD No (retry logic for updates/deletes)
UT Yes

15. Performance Read Write @Table Fast Fast #Table Fast OK ##Table Fast OK
TinTDB Fast OK
MO Fastest Fastest
MOD Fastest Very Fast
UT Fast Slowest

16. Create Table Time @Table µs #Table ms ##Table ms TinTDB ms MO seconds
MOD seconds
UT ms

17. Alternative Option

18. CTE – Common Table Expression
DEMO
WITH tempName AS (
SELECT … )
Do Something with tempName

19. Summary @Table small datasets in procedures,
logging of transaction steps
#Table all other cases
##Table sharing temp data between processes
TinTDB just don’t do/use it
MO staging if source grab is repeatable
high frequency
MOD staging if source grab is not repeatable
UT only is in memory is not available

20. THANK YOU! and may the force be with you…
Questions?
(9 to 5 5 days a week :-)
(24x7)