Unanswered Questions
16,528 questions with no upvoted or accepted answers
16
votes
0answers
945 views
Splitting Snapshot files with MaxBCPThreads for Transactional Replication
I've just set up a publication, and I'm attempting to get the snapshot to apply faster. So far the Distribution Agent is respecting the MaxBCPThreads settings, but the Snapshot Agent is not. I'm ...
10
votes
1answer
1k views
HADR high worker thread usage
Why would an availability group's number of worker threads in an HADR pool increase well beyond minimum usage of "typically, there are 3–10 shared threads" per replica?
In one case we've observed ...
9
votes
1answer
803 views
Where can I find the SQL-89 standard?
This question is different but similar to this request looking for SQL-86.
SQL 1989 is almost 30 years old. Is this spec freely available anywhere. The standard does not have a Wikipage or the like?
...
8
votes
1answer
136 views
MySQL deadlock: upsert query acquiring gap lock twice?
I am trying to debug a deadlock scenario which has been puzzling me for quite some time now. I am wondering if someone can shed any light into how this can happen.
Here is the deadlock output:
------...
8
votes
1answer
588 views
Database Stuck 'In Recovery' with command XTP_DB_RECOVERY
We recently converted a table to memory optimized data. Our backups have all ballooned (3x300GB files to 3x600GB files for Full, 3x50GB to 3x250GB for Diffs), and startup has been getting ...
8
votes
0answers
266 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 ...
8
votes
0answers
859 views
Why does RDS PostgreSQL always recover on restart?
I am running an RDS instance of PostgreSQL 9.6.3: select version(); returns PostgreSQL 9.6.3 on x86_64-pc-linux-gnu [...].
I have found that after issuing a stop from the RDS console followed by a ...
8
votes
1answer
768 views
Convert query in words to relational algebra
I have a follow-up question to a question I have previously asked on SO.
Instead of the query from my initial question, I want to convert the following into relational algebra:
List the names and ...
8
votes
1answer
3k views
How can client retrieve SQL Server public SSL certificate?
Can a user retrieve the connection certificate for an SQL Server instance (similar to how someone can retrieve an HTTP certificate)? If so, how?
Context
If encryption is requested by the SQL Server ...
8
votes
2answers
25k views
Why does CAST(1 AS SIGNED INTEGER) return a BIGINT on MySQL?
If I do CAST(1 AS SIGNED INTEGER) I always end up getting a BIGINT returned, for example:
$ mysql -u root -p --column-type-info
Enter password:
--- Copyright and help message snipped for brevity ---
...
7
votes
0answers
212 views
CMEMTHREAD waits during Index Optimisation in Availability Group
In a 3 node Availability group, a secondary replica will often become subject to redo lag due to the causes covered in Microsoft's documentation:
Troubleshoot: Changes on the Primary Replica are not ...
7
votes
0answers
208 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 ...
7
votes
4answers
2k views
SELECT query slow even with nonclustered Index and a full-text index
I am attempting to query between 0 and 65,000 rows from a table.
The server is using Microsoft SQL Server 2014, and I have no way to change the hardware on the server.
Schema
[Id] (PK) INT ...
7
votes
1answer
732 views
Postgresql with just index storage
I have a PostgreSQL table with a key (bigint) and a value (double). The table has tens of billions of rows. I have a single btree on the (key,value) for aid lookups by key. The table is never updated.
...
7
votes
1answer
91 views
Does MySQL/InnoDB use table caches when dealing with foreign tables?
TL;DR: Does a table referred to via schema.table get held in table cache?
I have a large number of client databases that our application connects to based on an http request. These are used for every ...
