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Questions tagged [database-internals]

For technical questions about the internal workings of the database engine.

15 questions with no upvoted or accepted answers
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7
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0answers
121 views

Constant Scan applying

This question is continuation of optimizer behavior exploration in regard to VALUES construct started here and here. I want to ask about VALUES and APPLY this time. Using CROSS APPLY to alias an ...
6
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0answers
727 views

Alwayson AG lease timeout and healthcheck timeout

We have a physical SQL Server 2016 Enterprise SP2 with two instances and each instance contains one AG. Sometimes it happens that one AG goes to resolving (without failover), the cluster resource is ...
6
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0answers
135 views

dm_os_memory_cache_clock_hands understanding

As I mentioned in this question I'm trying to understand the working of clock hands. Simply put clock hands move when there is memory pressure so that cache entries can be removed or the cost can be ...
4
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1answer
1k views

Does PostgreSQL/PostGIS use R-Tree or R*-Tree?

PostgreSQL and PostGIS offer to create indexes over GiST with pretty much the same code. On 2D items, "This gives R-tree behavior" is what it says in the PostgreSQL source comments. However, it is a ...
4
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0answers
223 views

Service broker internal spid hogging tempdb

We've recently decommissioned a rather badly implemented service broker setup after a number of near outages, however while doing my morning checks I've noticed that there are 2 Service Broker ...
2
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0answers
58 views

How is page data rearranged after clustered index is created?

Can anyone please explain what happens at the page level when clustered indexes are created? How do pages rearrange data once clustered indexes are created?
1
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0answers
19 views

DCM page in Filestream_Data_Filegroup

I'm doing some research about the DCM (Differential Change Map) page in SQL Server 2016. This is what I discovered so far: page type: 16 each DCM page covers a GAM interval each data file has a DCM ...
1
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0answers
589 views

Log file Zeroing

During the creation of the database, I am getting below mentioned information about log file zeroing and I have highlighted my understanding in bold fonts. 2015-08-23 12:42:36.850 spid51 ...
1
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0answers
164 views

Page Header DB Frag ID Property

I am using SQL Server version: Microsoft SQL Server 2012 - 11.0.2100.60 (X64). I created a single table containing one and only one integer-valued column. I then added one and only one row to the ...
1
vote
1answer
377 views

SSRS Encryption Key backup location

I would like to know if there is any metadata table/registry entry where we can find the backup location of SSRS Encryption Key. I am working on a power shell report to display the Encryption Key ...
0
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0answers
21 views

Trimming copy/delete mysql table rows using Trigger

I am using Freeradius AAA server on Ubuntu 18 server which uses mySQL ver 5.7.27 as DB to store entries. INNODB is being used. It have a table called radacct which stores users accounting /session ...
0
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0answers
26 views

Character set issue

Error 'Character set '#255' is not a compiled character set and is not specified in the '/user/share/mysql'. Facing error in replication channel from mysql 8.0.16 to mysql 5.7.25.Is there any ...
0
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0answers
18 views

Mysql 8.0.16 crash due to informatiin_schema.Keywords table

How to resolve issue of mysql 8.0.16 crash?mysql 8.0.16 crash many times and shown server logs due to invalid argument.and in error log query is select WORD from information_schema.KEYWORDS. how to ...
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63 views

Is there a way to make postgres “COUNT WHERE” query log(N)?

Afaik, now this request SELECT COUNT(*) FROM user WHERE rating > 50 looks like this: find an item with the value of rating 50(or greater) in our b-tree index, pretty fast. Iterate though all items ...
0
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1answer
55 views

LOAD DATA statement returns a syntax error a fraction of the time

MySQL 5.5.32, MyISAM A LOAD DATA INFILE statement usually executes and returns normally, succeeding at loading the data. On rare occasion it fails, returning a generic syntax error, always indicating ...