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Introduction to Showplan
Showplan is a feature in SQL Server to display and read query plans. While some of you may already be very familiar with Showplan, it is one of the most important diagnostic tools that we use in the...
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Viewing and Interpreting XML Showplans
As mentioned in our previous blog posting, SQL Server 2005 supports Showplan generation in XML format. XML-based Showplans provide greater flexibility in viewing query plans and saving them to files as...
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What's this cost?
Oftentimes when people include actual execution plan (Ctrl-M, see previous posts for a good primer on execution plans) while executing a batch in SQL Server Management Studio, and they see this "Query...
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Showplan Trace Events
Besides SSMS, another great tool available to database developers and DBAs to view query plans and troubleshoot query compilation or execution issues is the SQL Server Profiler. In the Profiler, all...
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Statistics Profile Output Formatting
Statistics profile output is an important tool when it comes to troubleshooting query plan issues. When enabled, it returns a textual representation of the query plan with a lot of detail about cost...
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Intro to Query Execution Bitmap Filters
One of the least understood Query Execution operators is the Bitmap. I'd like to give a fairly brief overview of how Bitmap filters are used, as well as some technical details about their limitations...
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Index Build strategy in SQL Server - Introduction (I)
Index Build strategy in SQL Server may vary depending on users needs. Each of these Index Build strategies may have different memory and disc space requirement. These different strategies will be...
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Index Build strategy in SQL Server - Introduction (II)
- Building Partitioned Index vs. Building non-Partitioned Index: The data of partitioned tables and indexes is divided into units that can be spread across more than one filegroup in a...
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Using ETW for SQL Server 2005
ETW stands for “Event Tracing for Windows” and it is used by many Windows applications to provide debug trace functionality. This “wide” availability is a key point of using ETW because it can help to...
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Query Execution Timeouts in SQL Server (Part 1 of 2)
This short article provides a checklist for query execution time out errors in Yukon. It does not touch the time out issues on optimization and connection. Before reading this article, you are...
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Index Build strategy in SQL Server - Part 1: offline, serial, no partitioning
Builder (write data to the in-build index) | Sort (order by index key) | Scan (read data from...
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Query Execution Timeouts in SQL Server (Part 2 of 2)
Checklist for time out errors Memory pressure: In most cases timeouts are caused by insufficient memory (i.e. memory pressure). There are different types of memory pressures and it is very important...
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Index Build strategy in SQL Server - Part 2: Offline, Parallel, No Partitioning
The type of parallel index build plan in SQL server depends on whether or not we have a histogram available with necessary statistics. Therefore, there are two broad categories of parallel index plans:...
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Index Build strategy in SQL Server - Part 2: Offline, Parallel, No...
Build (serial) (write data to the in-build index) | X (Merge exchange) / | \ Sort…...
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Index Build strategy in SQL Server - Part 3: Offline Serial/Parallel...
There are two main categories of partitioned index build: Aligned (when base object and in-build index use the same partition schema) Not- Aligned (when heap and index use different partition schemas...
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Index Build strategy in SQL Server - Part 3: Offline Serial/Parallel...
Aligned partitioned parallel index build In case of parallel build we scan and sort partitions in parallel and the actual number of sort tables existing at the same time will depends on the actual...
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Hash Warning SQL Profiler Event
One of the less well-known warning events that is logged to SQL Profiler trace is the Hash Warning event. Hash Warning events are fired when a hash recursion or hash bailout has occurred during a...
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How to Check Whether the Final Query Plan is Optimized for Star Join Queries?
The star join optimization technique is an index based optimization designed for data warehousing scenarios to make optimal use of non-clustered indexes on the huge fact tables. The general idea is to...
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Index Build strategy in SQL Server - Part 4-1: Offline Serial/Parallel...
Recall that in the previous posts on index build, we defined "aligned" as the case when base object and in-build index use the same partition schema, and "non-aligned" to be the case when heap and...
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Index Build strategy in SQL Server - Part 4-2: Offline Serial/Parallel...
Source PartitionedWhile the table is partitioned, we may want to change the way it is partitioned when building the new index. For example, by using the same partition function and scheme, the new...
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