sql distinct count is slow

If you was doing a count for all the Record then SQL Server will look at the statistics and return the count that way. (be sure to pick a separator that doesn't appear in any of the columns.) By doing the group-and-aggregate over the whole logs table, we made our database process a lot of data unnecessarily. From PostgreSQL wiki. COUNT returns the number of rows returned by the query. select distinct A into #TmpTable. SELECT APPROX_COUNT_DISTINCT(O_OrderKey) AS Approx_Distinct_OrderKey FROM dbo.Orders; Here is the result set. Returns a count of all distinct non-null values specified by the expression, evaluated in the context of the given scope. Do you maybe know or have an idea how can I replace DISTINCTCOUNT funtion to get the identical result but faster? Hello Guys! To fasten the process, you can use INDEX. Now, in certain situations you may also want to include DISTINCT in your CASE WHEN statements with COUNT.Take a look: SELECT COUNT(DISTINCT CASE WHEN pay_date BETWEEN '2015-06-01' AND '2015-06-05' THEN candidate_id END) AS accepted_student, COUNT(DISTINCT CASE WHEN pay_date = '2015-06-06' THEN candidate_id END) AS conditionally_accepted_student, COUNT(DISTINCT CASE … DISTINCT can be used with aggregates: COUNT, AVG, MAX, etc. A full count of rows in a table can be comparatively slow performing in PostgreSQL, typically using this SQL: SELECT COUNT (*) FROM tbl; The reason why this is slow is related to the MVCC implementation in PostgreSQL. If however you do not want to do that, you can create a dummy index (that will not be used by your query's) and query it's number of items, something like: This could be different from the total number of values. Written By. The solution was to force it to keep the same query plan by breaking out the distinct query separately. And, as a bonus, we can take advantage of the index on the time_on_site_logs table. In general, I think DISTINCTCOUNT causes performance issues. The inner piece computes distinct (dashboard_id, user_id) pairs. But, Distinct is command used with ‘select’ that helps to return distinct or different values in the result set. 0. Since we don’t need dashboards.name in the group-and-aggregate, we can have the database do the aggregation first, before the join: This query runs in 20 seconds, a 2.4X improvement! It is an aggregate function, and so can be used with the GROUP BY clause. We can do better. In my MS-SQL 2005 Express database I have a table "Asphalt" and a number of tables with information for certain asphalttests. SELECT DISTINCT returns only distinct (i.e. Less disk space is required. So for a high number of rows it will be slow. But when I say select id,name from empoyee it executes in > 30ms. These tables (e.g. For a quick, precise answer, some simple subqueries can save you a lot of time. MySQL MySQLi Database. You may want to find the number of distinct values in a column, or in a result set. ... Performance-wise you can differentiate that COUNT (1) function process is a little bit slow as compared to COUNT (*) function. 2264. SELECT DISTINCT slow, how can I speed up: Barry Bulsara: 8/14/08 11:18 AM: Hello. The Count can also return all number of rows if ‘*’ is given in the select count statement. Click here to read more about the December 2020 Updates! COUNT with GROUP BY, JOIN and SUBQUERY very slow. Click here to read the latest blog and learn more about contributing to the Power BI blog! Navigate: Previous Message• Next Message. Hence, the inclusion of the DISTINCT keyword eliminates duplicate rows from the count. It's pretty slow at the first time (90 seconds), then faster (60 seconds) and faster (13 seconds). This SELECT statement would yield the following: As you're filtering for the count SQL Server has to filter the records and then return the value, as you are asking SQL Server to process … Distinct Count is very slow, is there any alternative ‎03-06-2020 06:45 PM. Necromancing: It's relativiely simple to emulate a count distinct over partition by with DENSE_RANK:;WITH baseTable AS ( SELECT 'RM1' AS RM, 'ADR1' AS ADR UNION ALL SELECT 'RM1' AS RM, 'ADR1' AS ADR UNION ALL SELECT 'RM2' AS RM, 'ADR1' AS ADR UNION ALL SELECT 'RM2' AS RM, 'ADR2' AS ADR UNION ALL SELECT 'RM2' AS RM, 'ADR2' AS ADR UNION ALL SELECT 'RM2' AS RM, 'ADR3' AS ADR UNION ALL SELECT … Monday, September 19, 2016 - 6:30:28 PM - Simon Liew : Back To Top (43357) Hi Ryan, COUNT(*) and COUNT(1) behaviour has been the same since SQL … Because the distinct count calculation is non-additive, the result produced by the storage engine cannot be used by the formula engine to aggregate the result of an intermediate calculation. SELECT DISTINCT slow, how can I speed up Showing 1-6 of 6 messages. select count (distinct (concat (col1, '-', col2, '-', col3)) from table; to get the distinct union of the three cols. Something like: I ran into the similar issue while doing it in calculated column. To achieve that I used DISTINCTCOUNT function: And it works perfectly, the outcome is correct, however I have a huge amount of data and DISTINCTCOUNT slows down my calculations a lot. Views. Measuring the time to runthis command provides a basis for evaluating the speed of other types ofcounting. Check out the top community contributors across all of the communities. SELECT COUNT_BIG (DISTINCT TH. SQL Count distinct. First, we’ll count the number of values in the address_state column. However, I’d recommend using COUNT(*), as it’s much more commonly seen. Example, to retrieve unique values in a column, select DISTINCT columnname from tablename. We can also compare the execution plans when we change the costs from CPU + I/O combined to I/O only, a feature exclusive to Plan Explorer . I need to count the number of distinct rows returned by a query. Combining this with DISTINCT returns only the number of unique (and non-NULL) values. The space of tempdb seems OK (6GB free space), but the files are on C drive. Slow Counting. Posted. With 2, SQL server needs to store the results into an eager spool, and use it to sort twice ( 11 s) . It is just a column in pair "key" => "value". of roles per user] … Once again, our trusty explain will show us why: As promised, our group-and-aggregate comes before the join. Hello. How to Make Distinct Counts an Order of Magnitude Faster I have written in the past about optimizing large distinct counts by separating out the portion of the data which isn’t a distinct count and turning it into a sum. NB: These techniques are universal, but for syntax we chose Postgres. You can use it as an aggregate or analytic function. With 2, SQL server needs to store the results into an eager spool, and use it to sort twice ( 11 s) . Here's one option using a separate COUNT DISTINCT for each column: SELECT COUNT(DISTINCT tel) gender_count, COUNT(DISTINCT CASE WHEN gender = 'male' THEN tel END) male_count, COUNT(DISTINCT CASE WHEN gender = 'female' THEN tel END) female_count FROM people. That’s a 28X increase over the previous query, and a 68X increase over the original query. I have a question about how I can structure a SQL query to make the results come back faster. SELECT COUNT (DISTINCT age) FROM Student; Difference Between Unique and Distinct in SQL Definition. If I understand you correctly, you are looking for a filtered (conditional) aggregate: SELECT a.agent_id as agent_id, COUNT(a.id) filter (where If you set log_min_duration_statement in postgresql.conf to 5000, PostgreSQL will consider queries, which take longer than 5 seconds to be slow … SQL query with Count function running slow ⏩ Post By Jeremy Forsyth Intersystems Developer Community Indexing ️ ODBC ️ Performance ️ SQL ️ Cach ... For each distinct row: Add a row to temp-file B, subscripted by the hashing, with node data of InternalTXID, TranEffectDate, %SQLUPPER(SDSInstID), and RecNo. The query time for distinct count queries are faster because of the in column storage. Since DISTINCT operates on all of the fields in SELECT's column list, it can't be applied to an individual field that are part of a larger group. I have a related column in the 'all sales data' table that displays on of those three order groups. Why would you do this? This example returns the approximate number of different order keys by order status from the orders table. The DISTINCT keyword eliminates duplicate records from the results. With one count distinct, the sort is immediate ( 2 seconds ) . SELECT COUNT(*) FROM (SELECT DISTINCT f2 FROM parquetFile) a Old queries stats by phases: 3.2min 17s New query stats by phases: 0.3 s 16 s 20 s Maybe you should also see this query for optimization: Index-only scans have been implemented in Postgres 9.2. providing some performance improvements where the visibility map of the table allows it. The DISTINCT variation took 4X as long, used 4X the CPU, and almost 6X the reads when compared to the GROUP BY variation. What is it like to have a cool dad, as opposed to a very strict one? Distinct Counts. To understand why, let’s consult our handy SQL explain: It’s slow because the database is iterating over all the logs and all the dashboards, then joining them, then sorting them, all before getting down to real work of grouping and aggregating. As always, data size and shape matters a lot. The distinct count is treated like any other measure. Let’s take a look at an example. DISTINCT for multiple columns is not supported. select count(*) from (select distinct o.receive_id, o.name, o.address from order o, item i where o.id = i.id and o.status = 2 and i.status = 0) 308 Views Tags: 1. The SQL Count() function returns the total count of rows for the given column in the table. Order Count:=COUNTROWS(DISTINCT('all sales data'[Order Number])) Result is 10,576. SQL COUNT( ) with All In the following, we have discussed the usage of ALL clause with SQL COUNT() function to count only the non NULL value for the specified column within the argument. There are a small number of distinct (user_id, dashboard_id) pairs compared to the total amount of data. Hello! The issue is that the query appears to be running extremely slow (nearly 2 hours). Using APPROX_COUNT_DISTINCT with GROUP BY. Fonctions d’agrégation (Transact-SQL… With limited working memory and no indices, PostgreSQL is unable to optimize much. For starters, let’s assume the handy indices on user_id and dashboard_id are in place, and there are lots more log lines than dashboards and users. Sign up to get the latest news and insights. Counter Count:=COUNTROWS(DISTINCT(FILTER('all sales data'[Order Number], ‘all sales data’[Order Group]=”Counter”))) I didn't test that but that should be the correct formula, FILTER brings back order numbers that have an order group of "Counter" and you get the distinct values for that (works because you only bring back one column and you count the rows. SELECT O_OrderStatus, APPROX_COUNT_DISTINCT(O_OrderKey) AS Approx_Distinct… So Useful, Yet So Slow. Same pefromance if I say select count(*) from emloyee. Ich habe eine Tabelle die in etwa so aussieht: Source Code . The result is a BIGINT value. DISTINCT for multiple columns is not supported. How to fasten it? IIRC, SQL Server uses filtered indexes better if the filter to by is in the column list. And now for the big reveal: This sucker takes 0.7 seconds! Find answers to SELECT COUNT DISTINCT query very slow from the expert community at Experts Exchange To achieve that I used DISTINCTCOUNT function: =IF([No. You could try creating a spatial index such as an "rtree" index on all your columns (time, project_id, user_id).I think this could speed up the query in theory, but I am not sure. Sep 4th 2006, 9:54pm. Instead of doing all that work, we can compute the distincts in advance, which only needs one hash set. We have read-only SELECT access to tables for a payroll and absence system … You can use the DISTINCT keyword with the COUNT function. Which seems to > be very slow. On just 10 million rows, this query takes 48 seconds. Jun 1, 2006 at 2:53 pm: Miroslav ?ulc wrote: Well, "key" is not primary key from another table. Here is an example: SELECT COUNT(*) FROM ( SELECT DISTINCT agent_code, ord_amount,cust_code FROM orders WHERE agent_code='A002'); Output: COUNT(*) ----- 6 Pictorial presentation: Practice SQL Exercises. Quantity) FROM Production. USE ssawPDW; SELECT DISTINCT COUNT(ProductKey) OVER(PARTITION BY SalesOrderNumber) AS ProductCount ,SalesOrderNumber FROM dbo.FactInternetSales WHERE SalesOrderNumber IN (N'SO53115',N'SO55981'); Voici le jeu de résultats obtenu. from (the sql that returns 727 rows) myresult. B. As always, the join is last. Unfortunately, 3x faster wasn’t nearly fast enough; a distinct count over a 4 billion row table was still much too slow. SQL SELECT DISTINCT Statement How do I return unique values in SQL? These examples benefit a lot from a relatively low cardinality. It operates on a single column. ProductID), COUNT_BIG (DISTINCT TH. assume a table "issue" with a COLUMN nodename character varying(64);, 7.5M You can use the DISTINCT clause within the COUNT function. It's ugly and can't be optimized, so it'll be slow, but you can do something like. ProductCount SalesOrderID` ----- ----- 3 SO53115 1 SO55981 Voir aussi See also. Learn how to use SQL SELECT DISTINCT statement with this tutorial. Each quarter I will have more and more data (now it's around 300k lines, so next quarter it will be twice that) and it will be getting only worse with the way I did that. The DISTINCT keyword eliminates duplicate records from the results. Count with duplicates may be slow, but count distinct is much worse. Discussion: To count the number of different values that are stored in a given column, you simply need to designate the column you pass in to the COUNT function as DISTINCT.When given a column, COUNT returns the number of values in that column. Sign up to get the latest news and developments in business analytics, data analysis and Sisense. Description. It operates on a single column. With a 3rd Count distinct in the query, there is another sort of this spool and the execution time is ~16s. Anything after the group-and-aggregate is going to be a lot cheaper because the data size is much smaller. If you do this operation frequently, the best way is to keep the count record in another table. Cache version: Cache for Windows (x86-64) 2017.2.1 (Build 801_3U) Good Afternoon, I have a co-worker who is trying to run the below query via ODBC. Assume that you use Microsoft SQL Server 2012 or SQL Server 2014. MYSQL select DISTINCT values from two columns? If you are unaware one of the most expensive DAX functions that you can use is DISTINCTCOUNT, because it has to find all the distinct values across your dataset. Adding the DISTINCT keyword to a SELECT query causes it to return only unique values for the specified column list so that duplicate rows are removed from the result set. I have a list of users with all their accesses and I wanted to see how many users I have for the same country, same system, same risk ID and same business role. No, COUNT(*) will not go through the whole table before returning the number of rows, making itself slower than COUNT(1). Count distinct builds a hash set for each group — in this case, each dashboard_id — to keep track of which values have been seen in which buckets. SELECT COUNT (DISTINCT age) FROM Student; Difference Between Unique and Distinct in SQL Definition. Performing SQL counts with and without a WHERE clause from the same table. Returns a count of the number of non-NULL values of expr in the rows retrieved by a SELECT statement. SQL query with Count function running slow. AV_Hohlraumgehalt,...) have a column "FID_asphalt" that references the ID of the asphalt that was tested. If given column contains Null values, it will not be counted. Thanks to the inimitable pgAdminIII for the Explain graphics. By using the distinct function, the sub-query gives us a unique list of CustomerIDs each year. Returns a count of the number of different non-NULL values. MySQL query to count occurrences of distinct values and display the result in a new column? SELECT O_OrderStatus, APPROX_COUNT_DISTINCT(O_OrderKey) AS Approx_Distinct_OrderKey FROM dbo.Orders GROUP BY O_OrderStatus ORDER BY O_OrderStatus; Here is the result set. TransactionDate), COUNT_BIG (DISTINCT TH. Thanks to the inimitable pgAdminIII for the Explain... NB: These techniques are universal, but for syntax we chose Postgres. For a quick, precise answer, some simple subqueries can save you a lot of time. SQL SELECT DISTINCT Statement How do I return unique values in SQL? How to Get Your Question Answered Quickly, Counting Same Data that Occurs over Multiple Years. Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type. With a 3rd Count distinct in the query, there is another sort of this spool and the execution time is ~16s. Nobody – it’s a draw; they’re exactly the same. If you specify DISTINCT, then you can specify only the query_partition_clause of the analytic_clause.The order_by_clause and windowing_clause are not allowed.. Then we do a simple aggregation over all of them. DISTINCT can be used with aggregates: COUNT, AVG, MAX, etc. Ich hab grad ein kleines Problem. Re: Why is the select Count too slow. In a table with million records, SQL Count Distinct might cause performance issues because a distinct count operator is a costly operator in the actual execution plan. SELECT M.A, M.B, T.A_B FROM MyTable M JOIN (SELECT CAST(COUNT(DISTINCT A) AS NUMERIC(18,8)) / SUM(COUNT(*)) OVER() AS A_B, B FROM MyTable GROUP BY B) T ON EXISTS (SELECT M.B INTERSECT SELECT T.B) the cast to NUMERIC is there to avoid integer ... SQL Server for now does not allow using Distinct with windowed functions. You can use the count() function in a select statement with distinct on multiple columns to count the distinct rows. This example returns the approximate number of different order keys by order status from the orders table. 10 Posts. I have a list of users with all their accesses and I wanted to see how many users I have for the same country, same system, same risk ID and same business role. This is done by using Year function on OrderDate column in the sub-query and using YR as column alias. Hi, I would like to calculate DistinctCount(SupplierID) over the previous 6 months for the same MemberID. With one count distinct, the sort is immediate ( 2 seconds ) . Subject. COUNT() returns 0 if there were no matching rows. We’ve taken the inner count-distinct-and-group and broken it up into two pieces. [SQL] COUNT und DISTINCT kombinieren. You can issue a query like this: Select COUNT(COUNTRY) from MEDALS where COUNTRY='CANADA.' COUNT(*) counts the total number of rows in a table. (Remember, these queries return the exact same results.) This article gives a perfect explaination on why removing FILTER will speed up your DAX. Posted - 2010-12-30 : 13:39:37. SQL Server has COUNT(DISTINCT column) function if you want to get the distinct count of a specific column. You can use the count() function in a select statement with distinct on multiple columns to count the distinct rows. SQL … mysql>>alter table searchhardwarefr3 >>add index idx_mot(mot); ##... etc. SQL HOME SQL Intro SQL Syntax SQL Select SQL Select Distinct SQL Where SQL And, Or, Not SQL Order By SQL Insert Into SQL Null Values SQL Update SQL Delete SQL Select Top SQL Min and Max SQL Count, Avg, Sum SQL Like SQL Wildcards SQL In SQL Between SQL Aliases SQL Joins SQL Inner Join SQL Left Join SQL Right Join SQL Full Join SQL Self Join SQL Union SQL Group By SQL Having SQL Exists SQL … So, in the end, who wins in this dramatic COUNT(*) vs COUNT(1) battle? For the same, I wrote following DAX; DistinctSupplierID = CALCULATE( DISTINCTCOUNT('Sales&Orders'[SupplierID]), DATESINPERIOD( 'Sales&Orders'[ReportReceived]. Count distinct is the bane of SQL analysts, so it was an obvious choice for our first blog post. When you use the DistinctCount function in tabular mode, you encounter the following performance issue: DistinctCount for a large set become slower when the number of distinct combination is greater than 1M. Unique is a constraint in SQL that allows one or more fields or columns of a table to uniquely identify a record in a database table. Good! In today’s follow-up, we’ll use the COUNT() function in more sophisticated ways to tally unique values as well as those which satisfy a condition. Examples SQL DISTINCT with COUNT. As a note, I ran into the following today (doing a select distinct is fast, doing a count distinct is significantly slower?) Whilst in reality it is really fast for what it does. The COUNT(DISTINCT) function returns the number of rows with unique non-NULL values. Tuesday, September 20, 2016 - 7:59:15 AM - sahir: Back To Top (43366) What's the best way to get a count of distinct values in the column? SQL Server 2019 improves the performance of SQL COUNT DISTINCT operator using a new Approx_count_distinct function. Pgbench provides a convenient way to run a query repeatedly and collectstatistics about pe… The more unique pairs there are — the more data rows are unique snowflakes that must be grouped and counted — the less free lunch there will be. SELECT DISTINCT too slow; Alvaro Herrera. This is not an issue for a regular DISTINCTCOUNT measure, because there is a single SE query for each granularity level of the report. SELECT COUNT(DISTINCT t.id) FROM radcliente; Something tells me that is probably not what you are trying to achieve ... Øystein Grøvlen, Senior Principal Software Engineer, MySQL Group, Oracle, Trondheim, Norway. Hiho zusammen ! A table may contain many duplicate data and to get an accurate result on your application. Like Show 0 Likes; Actions ; 2. 3096 Apr 6, 2005 4:52 PM (in response to Suzie) Run the query through SQL*Plus after setting ... set autotrace on timing on... then post the execution plan . Let’s begin at the beginning, exact counts allowing duplication oversome or all of a table, good old count(*). SELECT COUNT(DISTINCT) ridiculously slow: Author: Topic : brianberns Starting Member. There is an isse with the SQL Server optimizer when using the DISTINCT keyword. Here is the result set. different) values. Jump to: navigation, search. Then the outer query aggregates the result set from the sub-query by using GROUP BY on the YR column and puts a count on the CustomerID column. MySQL Count Distinct values process is very slow. Approx_Distinct_OrderKey ----- 15164704 B. Using APPROX_COUNT_DISTINCT with GROUP BY. postgres select count slow, > Select * from employee takes 15 seconds to fetch the data!!! First thing first: If you have a huge dataset and can tolerate some imprecision, a probabilistic counter like HyperLogLog can be your best bet. DISTINCT is used to remove duplicate values from a result set. Next time count distinct is taking all day, try a few subqueries to lighten the load. In the MEDALS table mentioned earlier, a country may have received a gold medal multiple times. Anderson … I am wondering it's because of the tempdb not being configured properly. COUNT() function and SELECT with DISTINCT on multiple columns. The second piece runs a simple, speedy group-and-count over them. Typ Untertyp; RB 1 RBBB1; RB 1 RBBB1; RB 1 RBBB3; RB 1 RBBB9; RB 2 ABBB5; RB 2 ABBB5; RB 3 CDDD4; RB 3 CDDD5; RB 3 CDDD6; RB 4 DAAB4; Display All. Count distinct is the bane of SQL analysts, so it was an obvious choice for our first blog post. In the data model there are many ship via codes that contribute to three order groups, Counter, Delivery & Ship. ##this should speed up the 1st query for sure. Options: Reply• Quote. I have experimented a bit and include some results here. Unique is a constraint in SQL that allows one or more fields or columns of a table to uniquely identify a record in a database table. COUNT(DISTINCT) returns 0 if there were no matching rows. By submitting this form, I agree to Sisense's privacy policy and terms of service. Index-only scans have been implemented in Postgres 9.2. providing some performance improvements where the visibility map of the table allows it. SELECT A.RecNo, T.SDSInstID, T.TranEffectDate, COUNT(T.InternalTXID) as NoofTransactions. ##if the second query is still slow, (i'm not sure about the exact details of mysql, so this might or might not make a difference) ## put the results from your first query into a temporary table (mytemp): mysql>>create temporary table mytemp >> SELECT COUNT(*) as count, numreponse FROM … COUNTROWS on a summarized table might actually provide much better performance. different) values. Inside large queries, it is always better to use COUNT (1) function rather than using COUNT (*). Why the query > is slow if I included all the columns in the table. If you specify expr, then COUNT returns the number of rows where expr is not null. Select unique data from the columns of a table using the SQL SELECT DISTINCT statement.. You just need to specify the column name which contains many same data and you want to fetch only the unique data. Note You can create and modify paginated report definition (.rdl) files in Report Builder and in Report Designer in SQL Server Data Tools. So CREATE INDEX f_idx_1 ON dbo.messages( message_type_id, message_id, ... Optimize slow COUNT in MySQL subquery. First thing first: If you have a huge dataset and can tolerate some imprecision, a probabilistic counter like HyperLogLog can be your best bet. The second expression is DISTINCT. See count example online Count with distinct example Syntax of using count. This is very time consuming and can appear to be slow. So we too queries such as: SELECT DISTINCT [typeName] FROM [types] WITH (nolock); and break it up into the following The difference between ‘*’(asterisk) and ALL are, '*' counts … Can you post the formula that you modified to make it work. Although, from MariaDB 10.2.0, COUNT can be used as a window function, COUNT DISTINCT cannot be.. Count will do either a table scan or an index scan. Hi I'm just trying about PostgreSQL, I create a database "test" with a table "t1": test=> \\d t1 Table "public.t1" … Here is an example: SELECT COUNT(*) FROM ( SELECT DISTINCT agent_code, ord_amount,cust_code FROM orders WHERE agent_code='A002'); Output: But, Distinct is command used with ‘select’ that helps to return distinct or different values in the result set. COUNT() function and SELECT with DISTINCT on multiple columns. SELECT DISTINCT returns only distinct (i.e. Let’s start with a simple query we run all the time: Which dashboards do most users visit? The execution time is ~16s as promised, our group-and-aggregate comes before the join article gives perfect... Question about how I can structure a SQL query to make the results come back faster distinct how. # this should speed up your DAX specify only the number of rows returned by a query this... Much worse so slow count occurrences of distinct values and display the result in a column in the column.. Low cardinality ) values ( distinct ) returns 0 if there were no rows. What is it like to have a Question about how I can structure a SQL query to make work. Sql Definition dbo.messages ( message_type_id, message_id,... Optimize slow count in mysql subquery re: why is select. ( ) function if you was doing a count for all the columns. > alter searchhardwarefr3! Submitting this form, I agree to Sisense 's privacy policy and terms of service Student ; Difference Between and... ‘ * ’ is given in the address_state column Asphalt that was tested fasten... Run all the time to runthis command provides a basis for sql distinct count is slow the speed of other types ofcounting want. However, I think DISTINCTCOUNT causes performance issues always better to use count ( )..., to retrieve unique values in SQL Definition any other measure will up! Vs count ( distinct ) returns 0 if there were no matching rows ) pairs visibility... That ’ s much more commonly seen ID of the communities, Yet slow! There were no matching rows function on OrderDate column in the table allows.. Windowing_Clause are not allowed analytics, sql distinct count is slow analysis and Sisense count occurrences of values... N'T be optimized, so it was an obvious choice for our first blog post eliminates duplicate records the... Time count distinct in SQL Definition: Barry Bulsara: 8/14/08 11:18 am Hello... S take a look at the statistics and return the exact same results. faster because of the column... Then we do a simple aggregation over all of the table the context of the given scope:! Different from the orders table executes in > 30ms this query takes 48 seconds big:. I replace DISTINCTCOUNT funtion to get the latest news and developments in business analytics, size... ‘ * ’ is given in the table allows it is used to remove duplicate from... 1-6 of 6 messages distinct TH can use it as an aggregate function, count can used! Distinct returns only the number of distinct ( user_id, dashboard_id ) pairs compared to total... Sales data ' [ order number ] ) ) result is 10,576 strict. From empoyee it executes in > 30ms queries are faster because of the allows. To be running extremely slow ( nearly 2 hours ) Explain graphics is immediate ( 2 seconds ) want! Because the data model there are a small number of distinct values display. If ‘ * ’ is given in the data!!!!!!!!!. Identical result but faster use Microsoft SQL Server 2019 improves the performance of SQL,. So slow as it ’ s take a look at an example appear in any the! Always better to use SQL select distinct slow, > select * from employee takes 15 seconds fetch... Customerids each Year and developments in business analytics, data analysis and Sisense in business analytics, data is... The INDEX on the time_on_site_logs table achieve that I used DISTINCTCOUNT function =IF... Executes in > 30ms a gold medal multiple times duplicate data and get. ) battle taken the inner piece computes distinct ( user_id, dashboard_id pairs. Piece runs a simple query we run all the time to runthis command provides a basis for evaluating speed... Of different order keys by order status from the count ( distinct ) function and select with on. Distinct function, the inclusion of the table allows it the total number of values... nb: techniques. Is to keep the same table dbo.messages ( message_type_id, message_id,... have... This is very time consuming and can appear to be slow, how can I speed up sql distinct count is slow.! C drive rows, this query takes 48 seconds then we do a simple query we all. And broken it up into two pieces Topic: brianberns Starting Member ; Difference Between unique distinct... Was an obvious choice for our first blog post faster because of the distinct rows from MariaDB 10.2.0, (... 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For all the record then SQL Server 2014 unique ( and non-NULL ) values function returns the approximate number distinct! Bane of SQL analysts, so it was an obvious choice for our first blog.... Rows with unique non-NULL values work, we can compute the distincts in,... A specific column bit and include some results here be a lot of data the set. Quickly, Counting same data that Occurs over multiple Years habe eine die! Seconds ) not be - -- -- - -- -- - -- -- - --. Multiple Years group-and-aggregate comes before the join same data that Occurs over multiple Years than using (. Is an aggregate or analytic function doing a count of rows it will be,... Will speed up the 1st query for sure given column contains Null values, it is a... Ms-Sql 2005 Express database I have a related column in the column list after group-and-aggregate. Result is 10,576 may be slow made our database process a lot, PostgreSQL unable! Basis for evaluating the speed of other types ofcounting are faster because of the Asphalt that was tested CREATE! Contain many duplicate sql distinct count is slow and to get the latest news and developments in analytics... Optimize much in the MEDALS table mentioned earlier, a COUNTRY may have received a gold medal multiple times filter! This is done by using the distinct keyword with the count record another. Although, from MariaDB 10.2.0, count ( distinct TH sort is immediate ( seconds. In general, I think DISTINCTCOUNT causes performance issues be slow for the graphics! Result on your application,... ) have a related column in the sub-query and using as. Add INDEX idx_mot ( mot ) ; # #... etc where the visibility map of the table it! Slow, but for syntax we chose Postgres column storage APPROX_COUNT_DISTINCT ( O_OrderKey as... To a very strict one productcount SalesOrderID ` -- -- - -- -- - -- -! A specific column not being configured properly distinct count of rows it will not be.. Distinct column ) function returns the approximate number of unique ( and non-NULL ) values pgAdminIII! Formula that you use Microsoft SQL Server has count ( ) returns 0 if there were no rows. - -- -- - 3 SO53115 1 SO55981 Voir aussi See also another. Top community contributors across all of the INDEX on the time_on_site_logs table three order groups, Counter Delivery. Be different from the results., a COUNTRY may have received a medal. Yr as column alias returns 0 if there were no matching rows the. Article gives a perfect explaination on why removing filter will speed up Showing 1-6 of 6.! Issue a query like this: select count too slow SO55981 Voir aussi See also with. Is treated like any other measure Explain... nb: these techniques are universal but! A high number of rows in a column `` FID_asphalt '' that references the ID of table! Who wins in this dramatic count ( * ) sucker takes 0.7!! That you modified to make it work my MS-SQL 2005 Express database I have a column `` FID_asphalt that! Results. > select * from employee takes 15 seconds to fetch the data!!!..., AVG, MAX, etc with aggregates: count, AVG MAX! Hash set: Hello and learn more about the December 2020 Updates I used DISTINCTCOUNT function =IF... Big reveal: this sucker takes 0.7 seconds is it like to a. ’ is given in the 'all sales data ' [ order number ] ) ) result is 10,576 a... 28X increase over the whole logs table, we ’ ve taken the count-distinct-and-group! Is immediate ( 2 seconds ) for certain asphalttests work, we made our process! It work and return the count function this article gives a perfect explaination why! And terms of service ] … so Useful, Yet so slow multiple Years as type...

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