Unanswered Questions
16,907 questions with no upvoted or accepted answers
19
votes
0answers
1k 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 ...
12
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 ...
11
votes
1answer
309 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:
------...
11
votes
0answers
314 views
Constant Scan applying
This question is a continuation of optimizer behavior exploration in regards to VALUES construct started here and here. I want to ask about VALUES and APPLY this time.
Using CROSS APPLY to alias an ...
10
votes
0answers
13k views
Conceptual data model for a billing system
I am working on an existing MySQL database. My task is to create a new data model for a billing system on that existing application.
I have created a conceptual data model (click to enlarge):
##...
9
votes
1answer
245 views
2019 Enterprise - NOLOCK without NOLOCK, page latch time-out on tempdb and finally a dump
We have a very strange problem with a new SQL Server 2019 on 2 new physical machines:
Infrastructure:
Starting a new installation of SQL Server 2019 Enterprise (15.0.2000.5 / X64 on Windows Server ...
9
votes
0answers
125 views
Find friends of friends (recursively) efficiently using Postgresql
Objective: Users submit their Contact Books, and then the application looks for connections between users, according to their Phone Number. Something like "6 Handshakes" idea (https://en....
9
votes
1answer
873 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 ...
9
votes
0answers
3k views
PostgreSQL trigram GIST vs. GIN indexes
I have a PostgreSQL 9.1 database that contains 10M+ rows and some text fields that need similarity and %word%-like searches, so I decided to use trigram indexes.
Initially, I started to use GIN ...
9
votes
1answer
673 views
SSMS 2014 (and 2012) CTRL+TAB requires pressing enter
Sometime last week my CTRL+TAB behavior changed. I used to hit CTRL+TAB, release, then I would be in my previous document tab. Now I hit CTRL+TAB, release, and the nav window is still open requiring ...
8
votes
1answer
254 views
Efficiently store large list structure in RocksDB so that the data can be retrieved in pages
Description:
RocksDB is a key-value storage so we can simply serialise the list of objects & store the value corresponding to a key. This would be ok if the data in the list is small enough.
...
8
votes
1answer
664 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
237 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 ...
8
votes
0answers
1k 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
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 ...
