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23
votes
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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 ...
14
votes
0answers
380 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 ...
13
votes
2answers
184 views

How to limit memory consumption of mysql server to prevent OOM kills?

My MySQL instance is getting killed by the Linux oom_killer due to huge consumption of memory by mysql when inserting into longblob columns. This occurs when restoring a mysqldump which contains a ...
12
votes
0answers
2k views

Best practices for keeping protobuf spec in sync with relational database (e.g. PostgreSQL)

1. We have a schema definition in Google's Protocol Buffers format that we use to generate code for different gRPC implementations (Python, PHP) 2. We have a database (PostreSQL) that is initialized ...
12
votes
0answers
4k 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 ...
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
14k 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): ##...
11
votes
1answer
641 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: ------...
10
votes
0answers
280 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 ...
9
votes
1answer
485 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. ...
9
votes
0answers
7k views

DBeaver launch script from file

I'm trying to find a good alternative to SQL Developer for performing queries and scripts on Oracle instances. I find DBeaver to be an interesting tool, it has a lot of great features, BUT it seems ...
9
votes
1answer
1k 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
1answer
724 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
798 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
3k views

Working on a decision tree database design

I'm doing the conceptual model for a Decision tree database. The goal is store any Decision tree. I have four entity types: DecisionTree, Node, Branch and Leaf. Each Decision tree is composed of ...
8
votes
0answers
537 views

SQL Server Profiler: why the RPC Starting event does use an different decimal separator from SP Starting?

Trying to diagnose an problem, I've ran into that inconsistency. In SQL Server Profiler, the RPC Starting event uses the regional settings to write real numbers (example: in Portuguese(Brazil) 14.5 ...
8
votes
0answers
5k views

How to backup some selected tables, but not all, in pgAdmin 4?

In pgAdmin 3, the dialog to perform a backup allowed you to check and un-check the tables you wanted to be part of your backup. In pgAdmin 4, either I am unable to find this feature, or it is not ...
8
votes
5answers
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 ...
8
votes
1answer
1k 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. ...
8
votes
1answer
961 views

Oracle Ref Partitioning: Deadlock due to child table row migration

My ordering application uses Oracle 11g Database. This DB has a primary table ORDERS and multiple child tables like ORDER_DETAILS, PLAN etc. ORDERS table is LIST partitioned on STATUS column and all ...
8
votes
2answers
3k views

verify that mongos server is connected to config servers

I've been writing a backup script for sharded replica-sets and it's almost done. Except I can't seem to get it to successfully start the balancer backup after everything's all said and done. Here's ...
8
votes
1answer
1k views

Select * from statement execute very slowly, innodb io read speed is low

I have a very simple query " select * from ap_statistic " running in my servers. the servers have the same hardware and software configuration (CPU 8 core, mem :32G, OS: redhat 5.5, mysql version: 5....
7
votes
0answers
135 views

Does SQL Server 2019 have task scheduling differences between enterprise and standard editions?

In How It Works: SQL Server 2012 Database Engine Task Scheduling, Bob Dorr explains some of the changes for worker scheduler assignment in SQL Server 2012. He mentions that some of the improvements ...
7
votes
0answers
63 views

Why does the cast from double precision to numeric round to 15 significant digits?

The cast from double precision (float8) to numeric rounds to 15 significant decimal digits, thereby losing information. Clearly, more precision is possible. The cast to bigint (for values within its ...
7
votes
1answer
91 views

Why does only one version of these procedures get blocked under moderate load?

The table: CREATE TABLE [dbo].[Session] ( [SessionId] UNIQUEIDENTIFIER NOT NULL, [CID] INT NULL, [DEST] VARCHAR (50) NOT NULL, [...
7
votes
1answer
660 views

SSIS Package Not Being Deployed

I have an issue with an SSIS package, that when deployed via VS2017 to the integration services catalog is not actually being deployed. This is an individual package deployment, and not a project ...
7
votes
0answers
3k views

Why is Insert-Ignore so expensive in MySQL?

TL;DR: Inserting a large number of rows with no collisions is MUCH faster than (not) re-inserting the same rows, BOTH using the INSERT IGNORE syntax. Why is this? I would assume that the index lookup ...
7
votes
0answers
862 views

Extended Events - sqlserver.process_login_finish Not Firing?

We're trying to see whether a client is able to reach a database server, as it's receiving error: [DBNETLIB][ConnectionOpen (Connect()).]SQL Server does not exist or access denied. The error ...
7
votes
0answers
1k views

How to measure the memory usage of a Mongodb aggregation?

I recently started running into the Sort exceeded memory limit of... exception on an aggregation pipeline in MongoDB. I got around this by setting AllowDiskUse=True for the aggregation. However, I ...
7
votes
0answers
700 views

How to minimize access exclusive table locks while reducing bloat or ALTER (ing) a table?

In some circumstances, I've been told not to do a VACUUM FULL (or CLUSTER) of a table that is in production, because that will exclusively lock it for longer than wished. The same might apply to ...
7
votes
2answers
36k views

The INSERT/UPDATE/DELETE permission was denied on the object 'TheTable', database 'TheDb', schema 'dbo'

I have two SQL Server user accounts on a database that behave differently on INSERT / UPDATE / DELETE. SQL Server version is 2008 R2 (10.50.4042, 64 bits). UserA can do these commands (on any table). ...
7
votes
0answers
12k views

Generate UUID v4 automatically in MySQL

Is it possible to generate a UUID version 4 (completely random) in MySQL? I would like to use it as a primary key. Use Case Many systems will insert to the table, some may specify a UUID when ...
7
votes
0answers
581 views

Inconsistent equality checking of Unicode text in Postgres 9.5?

Using PostgreSQL 9.5. It seems like Postgres is being inconsistent with how it compares strings similar to لى. A unique constraint is considering some strings equal that GROUP BY is considering ...
7
votes
1answer
3k views

MySQL query to create a Matrix view using pivot

I have a table with the following fields: p1 p2 s1 s2 where p1 -> player1, p2 -> player2, s1 -> game1, s2 -> game2 The number of players can vary from 3 - 10. The table have the results between them....
7
votes
1answer
104 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 ...
7
votes
1answer
1k views

Change Tracking across several Tables

I'm looking into providing DB level change tracking within my system. I need to be able to track changes at an entity level, rather than just individual tables. Right now, we have triggers on each of ...
7
votes
1answer
973 views

RDS MYSQL instance rebooted and won't load INNODB table

So my production db in RDS apparently either crashed or was rebooted during a version update, and upon being restarted mysql couldn't load one of the innodb tables: as evidenced by the following error ...
7
votes
2answers
112 views

Changes access method for non-correlated subquery

Oracle 11g R2 Unfortunately our application has per row security "features". We have a query that looks about like this: Bad, slow: SELECT someRow, someOtherRow FROM bigTableA a WHERE EXISTS ( ...
6
votes
0answers
487 views

SQL Server 2019 service terminated unexpectedly at startup but manually starts

I've had a SQL Server 2019 server working great for the past few months, but it started stopping by itself since last Friday. This morning, I installed latest cumulative update on it. Here is my ...
6
votes
0answers
242 views

Using a Table as a Queue without sp_getapplock/sp_releaseapplock

I have a list of commands I need to execute, all of which are contained within a table I've named myQueue. This table is a little unique in that some commands should be grouped together such that ...
6
votes
0answers
2k views

How to control how JSON_ARRAYAGG orders results

I am testing MySQL JSON_ARRAY and JSON_ARRAYAGG functions in order to move some application expensive processes to SQL stored functions. In the following e-commerce application example, I am trying ...
6
votes
0answers
644 views

SQL Server 2012+ & Service Broker: SSBDT Spam ending conversations after sending message to NULL conversation_handle

I'm mostly posting this for community awareness, but feel free to give feedback if you think there is a solution other than coding around the problem as we are doing. Crossposting this from my bug ...
6
votes
1answer
9k views

Restore mongoDB by --repair and WiredTiger

We accidentally deleted the directory rm -rf /data/db which was our MongoDB path, and thanks to extundelete, we recovered it and got the directory /data/db. Here are our files in the directory, and ...
6
votes
0answers
1k views

AWS RDS postrgres massive disk use, small tables

I can't figure out why our AWS postgres server has consumed all of it's space. We just had to up the storage space allocated to it, but can't find any hint from postgres that it's using that much ...
6
votes
0answers
218 views

Using the Schema Generation Wizard to regenerate a previously-generated schema

Lately, I've been trying to clean up a group of projects that my company received from an outside contractor. Among them is an SSAS cube, with an associated data warehouse. The contractors generated ...
6
votes
0answers
572 views

Postgres 10 Logical Replication without truncating existing table

I have been fooling around with Postgres 10 logical replication, trying to learn about it and potentially apply it to a couple of projects. I have observed something that I am wondering about, but I ...
6
votes
0answers
1k views

RDS (MySQL): Swap usage growing but plenty of freeable memory?

We run a db.m4.10xlarge instance on Amazon's RDS. It runs 3 fairly busy databases and has a replica instance connected to it. Over the last few weeks I noticed the swap usage has been steadily rising ...
6
votes
0answers
346 views

UUID V1 and V4 bloats substantially after sequntial inserts and deletes. Why is it so, compared to serial and temporal BTree (which does not bloat)?

I am trying to understand the impact of deletions to bloat of tables and indexes after large number of inserts and deletes. The inserts and deletes are following a rather strict pattern: first the ...
6
votes
0answers
2k views

SQLPackage : Import or Export SQL Azure BACPAC without users

I know how to use SQLpackage.exe. I can export from SQL Azure and create a bacpac. I can also Import to SQL Server via SQLPackage.exe. I want to export or import without the users in the database. The ...
6
votes
0answers
587 views

CHANGE_TRACKING_CURRENT_VERSION() incorrect on database in standby

We are using a change tracking solution to export increments for BI purposes for years now. But it was running directly on the production database. To lower the load on the system we wanted it to run ...

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