Filtered Statistics in SQL Server
In SQL Server, Filtered Statistics can improve cardinality estimation, i.e. when joining lookup table, or while joining fact table and dimension table. For this reason, SQL Server supports the...
2016-05-15
11 reads
In SQL Server, Filtered Statistics can improve cardinality estimation, i.e. when joining lookup table, or while joining fact table and dimension table. For this reason, SQL Server supports the...
2016-05-15
11 reads
In SQL Server, for insert into select statements, when the target for insert into is temporary table, the select statement can execute in parallel. When the target is table...
2016-05-15
16 reads
SQL Server creates and maintains statistics for temporary tables, which lead to better cardinality estimation and optimal execution plan generation. Table variables have no statistics, which can result in...
2016-05-15
10 reads
In SQL Server, ASYNC_NETWORK_IO wait time can be high due to slow network, like when the database is in the cloud and the application is on premise. Furthermore, it...
2016-05-15
25 reads
Resource Governor in SQL Server provides CPU, Memory and I/O throttling. In SQL Server 2014 and earlier, CPU throttling works only for similar kind of workloads and not for...
2016-05-14
10 reads
SQL Server supports row and page compression on tables, indexes and partitions. This can lead to reduced I/O and better performance. However, it can also result in additional CPU...
2016-05-10
25 reads
When you use ODBC or SqlClient to access data from SQL Server, by default the query will be cancelled if there is no response from the server within a...
2016-05-09
29 reads
The SQL Server 2014 Buffer Pool Extension feature can extend the buffer pool space on to Solid State Drive (SSD), where data and index pages can be cached. There...
2014-12-04
23 reads
In NUMA (Non-Uniform Memory Access), processors in the same physical location are grouped in a node which has its own local node memory. In a NUMA based system, there...
2014-12-04
38 reads
SQL Server 2012 brings a new feature called Indirect Checkpoint. You can read more about it here: http://msdn.microsoft.com/en-us/library/ms189573.aspx. With Indirect Checkpoint, you get smaller and too many I/Os Checkpoint...
2013-03-19
14 reads
By HeyMo0sh
Over time, I’ve realised that one of the hardest parts of cloud management isn’t...
By HeyMo0sh
One of the biggest challenges I’ve faced in cloud operations is maintaining clear visibility...
By Steve Jones
I come to Heathrow often. Today is likely somewhere close to 60 trips to...
Comments posted to this topic are about the item Fun with JSON II
Comments posted to this topic are about the item Changing Data Types
Comments posted to this topic are about the item Answering Questions On Dropped Columns
I have some data in a table:
CREATE TABLE #test_data
(
id INT PRIMARY KEY,
name VARCHAR(100),
birth_date DATE
);
-- Step 2: Insert rows
INSERT INTO #test_data
VALUES
(1, 'Olivia', '2025-01-05'),
(2, 'Emma', '2025-03-02'),
(3, 'Liam', '2025-11-15'),
(4, 'Noah', '2025-12-22');
If I run this query, how many rows are returned?
SELECT t1.[key] AS row,
t2.*
FROM OPENJSON(
(
SELECT t.* FROM #test_data AS t FOR JSON PATH
)
) t1
CROSS APPLY OPENJSON(t1.value) t2; See possible answers