Questions tagged [limits]

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Very slow MariaDB query when adding ORDER BY/LIMIT but there are no rows

I am facing an issue with MariaDB 10.1 on a log table with the following (simplified) structure: CREATE TABLE logs ( log_id INT UNSIGNED AUTO_INCREMENT PRIMARY KEY, log_date TIMESTAMP DEFAULT ...
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0 votes
1 answer
53 views

Best practice for SQL table names when using sub namespaces that exceed maximum table name length

I have a MySQL database that includes many tables named according to a namespace that uses sub names and underscores (_ as in a_b_c), such as the following: life_domain_kingdom_phylum ...
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  • 124
2 votes
1 answer
39 views

Limiting the number of records from nested INNER JOIN table

The context is as follows: We have 3 tables: We'll call them A,B and C. A has a foreign key referencing table B, we'll call it "bId". The relationship is a ManyToOne. (One record in B can ...
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mySQL Query with a LIMIT on a row value

I am trying to replace a lot of queries like this with a single query. SELECT * FROM y WHERE x = a ORDER BY timestamp LIMIT 50 SELECT * FROM y WHERE x = b ORDER by timestamp LIMIT 50 SELECT * FROM y ...
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1 answer
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data model limit rows per user

This is regarding to postgres that I was asked to create data model which has a relationship with user. For example a new data model called Comment M:1 User, but while creating the data model is it ...
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  • 115
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1 answer
58 views

Determine Available Blocks of Contiguous Ids

We have a SQL Server table that has an int autoincrement primary key column on it. The table's primary key space is fragmented. For example, ids 1 through 10 are in use but then ids 11 through 100,000 ...
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58 views

PgBouncer Pool configurations

I have installed PgBouncer because of too many connections on database server. How can i check if BgBouncer pool is working correctly. When i perform SELECT * FROM pg_stat_database order by ...
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0 votes
1 answer
29 views

Fill remaining LIMIT rows selection if conditions met are less than LIMIT number

I have a MySQL database with data in it. They all have locations (London, Liverpool, etc), I want a query to select 10 random rows with a location (for example London), and if there aren't enough to ...
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  • 21
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1 answer
240 views

How to use ORDER BY and LIMIT inside JSON_AGG

I have a query which returns a desired output. SELECT shop, JSON_AGG(item_history.* ORDER BY created_date DESC) as data FROM item_history GROUP BY shop; Results: [ { "shop&...
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  • 3
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1 answer
23 views

MySQL replication username

What is the difference in using these two approaches when setting master-slave replication: Setting the binlog-do-db option on the master to choose which DBs are going to be replicated; Creating a ...
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  • 111
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2 answers
64 views

How to limit tree traversal in case of loops?

So I want to limit tree depth traversal (as the simplest recursion killer tool). Example code that turns normalized records into tree: CREATE TABLE items ( item_id serial PRIMARY KEY, title ...
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postgresql, connection limit for different roles

Is possible setup in postgresql.conf connection limit for specified role globally (in some .conf file) or individually? For example, I have 3 roles and max_connections = 600. Need to setup max 10 ...
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  • 153
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1 answer
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LIMIT and OFFSET a complex query

I have a query generated by a ORM (Sequelize), i ran into an issue where sequelize fails, look at those issues. https://github.com/sequelize/sequelize/issues/7344 https://github.com/sequelize/...
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1 vote
3 answers
113 views

How to not allow to insert a new record if count of current records exceeds a specified limit

I have two tables as the following team `id` BIGINT PRIMARY KEY AUTO_INCREMENT, `name` VARCHAR(255) NOT NULL, `member_limit` INT NOT NULL team_member `id` BIGINT PRIMARY KEY AUTO_INCREMENT, `team_id` ...
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2 votes
1 answer
121 views

Mysql self Join query with Limit never terminates

I'm running an experiment with the query Select Distinct table_1.id1, table_2.id1 FROM image as table_1, image as table_2 WHERE table_1.id2 = table_2.id2 LIMIT K; When I run the query ...
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0 votes
1 answer
42 views

updating n number of records mysql database

I want to update n number of records in table using a query like below, but it will return an error since in mysql, it is not allowed to use value after the limit key update producedItem pi inner ...
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0 votes
1 answer
34 views

MySQL apply LIMIT and OFFSET to a selected table, rather than to the result set

I have 3 tables as below. mysql> describe IDN_CONFIG_RESOURCE; +---------------+--------------+------+-----+-------------------+-------+ | Field | Type | Null | Key | Default ...
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1 answer
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Display Top X results for each unique value

I am trying to figure out how I can output any machine that has had the latest 3 backups be larger than 10GB. My SQL Table looks similar to the below table: ComputerID | BackupImageName | ...
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1 answer
245 views

How does adding LIMIT work with Where conditions in mysql?

In my database, there is only one record which satisfies the condition iv_title = 'ball skills'. Now I'm executing the following query : SELECT * FROM `imageAndVideo` WHERE `iv_title` = '...
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1 vote
0 answers
22 views

Set Maximum Tables In A Database [duplicate]

I need to set up a MySQL database with a maximum number of tables which can be created in it. For example, if I have my maximum at 5 tables for a single database, and someone attempts to create a 6th ...
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0 votes
1 answer
66 views

Distinct result with row_id for limit query

There are 2 tables: CREATE TABLE sample1 ( id int, name varchar, score int, mode int ) CREATE TABLE sample2 ( id int, mode int ... ) I need to select distinct name with MIN(score) and ...
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  • 103
1 vote
1 answer
16k views

Limit left join for multiple rows

Since MySql doesn't support main alias reference in subquery is a bit challenging to create query with multiple rows where you have to limit rows of left join tables. Let's overview simple example. ...
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  • 113
2 votes
2 answers
437 views

Predicting the primary keys exhaustion in MySQL based on rate of insertion

We are running out of primary keys for our table in production. We do not want that to occur again. So we need a mechanism to alert us when we are running out of primary keys based on the rate of ...
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  • 21
1 vote
0 answers
605 views

SQL Server Express 2017 database size limitation

I have a database hosted on SQL Server Express 2017. The size was small like 200MB. Today I have copied 24GB tables to the same database from external database hosted on different server. The ...
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  • 139
0 votes
1 answer
163 views

MySQL logging max_questions resource

How would I know in MySQL if the user has exceeded his max_queries per hour? I know that I can see this error on the client side, but I just want to know that before client is reporting to me, ...
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0 votes
1 answer
3k views

Limit groups of results based on a column value

I'm not sure I formulated the question properly, but anyway. I have a table with level-2 comments, some of which, expectedly, have the same comment_parent column value. How do I make a SELECT query ...
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  • 103
1 vote
1 answer
36 views

What happens if I load last 10 rows then next 10 after other rows are inserted?

What if I had a PHP script that had a pagination that loads last 10 rows then page two loaded next 10 in DESC order, but before loading next 10 on page 2, other 10 rows were added to the table? What ...
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3 votes
1 answer
18k views

Alternate to use LIMIT in subquery in mysql?

I have 2 tables, Resource and views and I'm trying to get the list of all the items from Resource table whose ran_resId don't match with the ran_resId of last 2 records of views table. I'm trying to ...
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  • 131
0 votes
1 answer
85 views

Does switching from INT to BIGINT entails significant downtime?

Hypothetically, if your INT column already has 4 billion rows, how long is the process of converting that column to BIGINT? I know this will depend on server resources but I just want to have a ...
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  • 159
1 vote
1 answer
195 views

Delete from table using FK columns, JOIN and LIMIT

This query below will never complete, since it always looks at the first 100,000 (user_type, user_ids). How can I write this to delete 100,000 records from the table with the FK reference (Product) to ...
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  • 121
12 votes
1 answer
9k views

Why *not* ERROR: index row size xxxx exceeds maximum 2712 for index "foo"?

We have repeatedly seen failing attempts to index columns with values exceeding a maximum size. Postgres 10 has this kind of error message for it: ERROR: index row size xxxx exceeds maximum 2712 for ...
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19 votes
2 answers
20k views

MongoDB terminates when it runs out of memory

I have the following configuration: a host machine that runs three docker containers: MongoDB Redis A program using the previous two containers to store data Both Redis and MongoDB are used to ...
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7 votes
2 answers
5k views

Postgres slow query with order by, index and limit

I am trying to improve the performance of a postgres(9.6) query. Here is my schema and table contains about 60 million rows. Column | Type | Modifiers -------...
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  • 71
17 votes
5 answers
12k views

SQL Server Error 8632 due to over 100,000 entries in WHERE clause

My problem (or at least the error message) is very similar to query processor ran out of internal resources - extremely long sql query. My customer is working with an SQL select-query, containing a ...
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  • 333
2 votes
1 answer
120 views

Is there a server option which limits the amount of rows returned by a remote query?

I have an issue where a system on our network is making a query (select * from table) which might result in 0 to 70k rows being returned. For large result sets, say around 50k, the calling system is ...
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1 vote
1 answer
218 views

Is it possible to limit concurrent aggregations in Mongo?

When clients makes certain requests, our service sends aggregation queries to Mongo. Some of these aggregations take longer than others. Usually this is fine, but occasionally multiple heavy ...
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5 votes
1 answer
3k views

Limits of applock in MS SQL Server

Microsoft SQL Server offers an arbitrary application-defined locking mechanism through the sp-getapplock command and related commands. The key, or resource_name, is specified as a string, a varchar ...
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4 votes
2 answers
32k views

MySQL LIMIT within JOIN

I have an 1:m association. symbols table has many rows in company_key_statistics table. company_key_statistics has column createdAt which is timestamp indicating when row has been created. I need to ...
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4 votes
1 answer
2k views

PostgreSQL Size Quota on Table or Schema

How do one limit the size of a PostgreSQL table? (or schema) Limit in either bytes or rows would be OK. I'm starting to think that there's no easy and obvious solution. I have a lot of identical ...
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3 votes
1 answer
1k views

MySQL 5.5 vs 5.6,5.7 above same database same query but different output, limit have duplicated ID

I am using Running same source code and same database for WordPress, only the mysql version is different. It make my pagination post have duplication. Here is what I found out. Any idea how to solve ...
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1 vote
2 answers
2k views

Is it bad form to use "LIMIT 1" on queries that should only return one row anyway? [closed]

If you have a query like this: SELECT * FROM table WHERE primary_key_column = 123 LIMIT 1; What do you make of the LIMIT 1? It is technically not necessary, as we are selecting on a unique column. ...
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3 votes
1 answer
2k views

Limit number of simultaneous queries by user

I am looking for way to allow one user to execute maximum 3 queries at the time. Is there such possibility in Postgres? Due to some technial difficulties I cant limit number of connections, and the ...
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  • 33
0 votes
2 answers
3k views

Row size too large (> 8126)

I have a table with 156 columns and most of them are either VARCHAR(1000) or TEXT. Now, when entering data into one such row, I get mysql_error() = Row size too large (> 8126). Changing some ...
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  • 225
6 votes
1 answer
13k views

UPDATE Only one row (using update and join)

I'm trying to get a fast, simple sql query to update only one row at a time while using join too. I have tried LIMIT, but to no success. Query: UPDATE table1 JOIN table2 ON table2.col=table1.col ...
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1 vote
0 answers
64 views

Resource cost of database per tenant

I've read that one big disadvantage of the database per tenant model in multi-tenant applications is the extra resource cost of having many (potentially thousands or tens of thousands) databases ...
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2 votes
2 answers
6k views

mysql max_connections limit reset

Last week I updated mysql max_connections to 1000 from 151 using use mysql; set global max_connections = 1000; Today there was a power outage at the hosting company and the servers shut down and ...
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2 votes
0 answers
248 views

Oracle to SQL server replication recent data filter options

The current setup: A live application DB is on an oracle server, which has a nightly replication over to an SQL server that users (read me) can use to bash out reporting from. The issue is due to ...
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2 votes
1 answer
4k views

In MySQL, what's the most efficient way to query an entire table in chunks?

If I have a table User is it faster to do something like: SELECT * FROM user WHERE id > ? ORDER BY id LIMIT 10000 (With each subsequent query using the previous last row's id as the param) Or to ...
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2 votes
2 answers
4k views

Express edition core limits ambiguity

We have an application that uses MSSync to download data from a server into a client's SQL Server Express 2005. The client's have a dual core with hyperthreading so, a total result of 4 cores. I have ...
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  • 123
1 vote
1 answer
1k views

Will MongoDB exceed the 64000 ulimit threshold?

We are using MongoDB as a newbie and today we have exceeded the ulimit of the system causing chaos and panic all around. However I have fixed it by increasing the hard and soft limits like below. ...
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