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SQL Server 2019 CTP3.1 introduced an optimization to address last-page insert contention. This takes the form of an index option called OPTIMIZE_FOR_SEQUENTIAL_KEY. One imagines this could be an ...

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 ...

In Amazon RDS SQL Server (any version/edition), create a temp table and update statistics on it. This works fine: IF OBJECT_ID('tempdb..#t') IS NOT NULL DROP TABLE #t; GO CREATE TABLE #t (id INT ...

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 ...

The From Clause Documentation starting with SQL Server 2008 briefly mention 3 join hints and their basic mechanisms: Reduce Replicate Redistribute However there does not seem to be much information ...

Context I have stumbled on an issue in SQL Azure where the Sort-operator is spilling over into TempDB due to poor row estimates. We are querying a master table that is joined with a number of detail ...

Let's say I have a table A, that has two columns: one is an ID for ThingA, and one is an ID for ThingB. The primary key is (ThingA, ThingB). Next, I have a second table, but this time it's restricted ...

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 ...

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 --- ...

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 ...

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 ...

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 ...

I'm trying to force a plan using query store but it keeps failing with reason 8695 according to data in SYS.QUERY_STORE_PLAN the last_force_failure_reason_desc is 'General_Failure'. Does anyone know ...

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 ...

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 ...

I am working on 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): ...

I've been writing a backup script for sharded replica-sets and it's almost done, except that I can't seem to get it to successfully start the balancer back up after everything's all said and done. ...

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 ...

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. ...

I've got a FTS Catalog on a table containing ~106 row. It used to work like a charm, but lately, for an unknown reason it started to get very bad (query >30 sec) performances randomly. Reading ...

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 ...

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 ...

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 ...

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 ...

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 ...

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 ...

I am attempting to query a maximum of 65,000 records in a database (minimum of 0). The server is using MS SQL Server 2014, and I have no way to change the hardware on the server. Schema [Id] (PK) ...

I'm trying to create an index concurrently. CREATE INDEX CONCURRENTLY blocks_expr_idx6 ON blocks USING btree ('blah') WHERE "type" = 'user root'; 12 hours after I ran the query, if I run \d blocks ...

In PostgreSQL 9.5, to monitor streaming replication lag, I use a combination of: pg_current_xlog_location() pg_last_xlog_replay_location() pg_last_xact_replay_timestamp() The first two functions are ...

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. ...

I was hoping someone here might have encountered this sort of issue and if so what did you do to fix it? Here's some details: DB server: SQL 2014 Enterprise (12.0.4100.1) OS: Windows 2008R2 ...

Following the the info in posts like these i would like to use the role system and policies, i.e. each user in my system would have a db role. I want to model the following properties but i can't come ...

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 ...

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 ...

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....

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? ...

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 ( ...

I am working on an ERD which represents the relationships between entities in a Web development company behavioral model. There I have entities like: Customer Service ----------- (like: web ...

I have been seeing some concerning behavior in the SQL Server memory caches on one of our production servers. We are on SQL Server 2014 SP2 Enterprise Edition, 16 cores, 400GB RAM (300 GB dedicated to ...

Trying to get better at designing databases, I noticed I'm always stuck trying to solve variations of the exact same problem. Here is an example using common requirements: An online store sells ...

I have a SQL 2012 server that is throwing the following error every 5 minutes or so: Error: 17886, Severity: 20, State: 1. The server will drop the connection, because the client driver has ...

I am looking to introduce a test driven design style to writing my stored procedures for a postgresql database implementation. I have seen that pgTap is a popular unit testing tool for postgres and ...

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 ...

As an analyst I love having the ability to turn up the work_mem on occasion when a big sort or index build is in the offing. As a DBA, the idea of random users being able to request an arbitrarily ...

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 ...

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 ...

Running SQL Server 2012 standard, using both replication data and log shipping. Transaction log backups are created every few minutes. This question is NOT about the amount of space reported by the ...

I have two tables and a trigger and am inserting values in ProjectsTable like this: CREATE TABLE ProjectsTable ( ProjectID NUMBER(6) NOT NULL, ProjectName VARCHAR2(200) NOT NULL, Cost ...

I have a 3 node cluster and the 2 secondaries initially went into SUSPECT mode due to a deadlock. I tried to resume both and only one caught up while the other is continuously deadlocking. I have to ...

I've set up a MySQL "cluster" (four CentOS 7 servers running MySQL 5.7.19) using Group Replication in multi-primary mode, but I can't get it to accept writes from more than one thread at a time. This ...