I am having a complete nightmare with my application. I haven't worked with datasets this big before, and my query is either timing out or taking ages to return something. I've got a feeling that my approach is just all wrong.
I have a payments table with a postcode field (among others). It has 40,000 rows roughly (one for each transaction). It has an auto-inc PRIMARY key and an INDEX on the postcode foreign-key.
I also have a postcodes lookup table with 2,500,000 rows. The table is structured like so;
postcode | country | county | localauthority | gor
AB1 1AA S99999 E2304 X 45
AB1 1AB S99999 E2304 X 45
The postcode field is PRIMARY and I have INDEXes on all the other fields.
Each field (apart from postcode) has a lookup table. In the case of country it's something like;
code | description
S99999 Wales
The point of the application is that the user can select areas of interest (such as "England", "London", "South West England" etc) and be shown payments results for those areas.
To do this, when a user selects the areas they are interested, I then created a temp table, with one row, listing ALL postcodes for the areas they selected. Then I LEFT JOIN it on to my payments table.
The problem is that if the user selects a big region (like "England") then I have to create a massive temp table (or about 1 million rows) and then compare it to the 40,000 payments to decide which to display.
UPDATE
Here is my code;
$generated_temp_table = "selected_postcodes_".$timestamp_string."_".$userid;
$temp_table_data = $temp_table
->setTempTable($generated_temp_table)
->newQuery()
->with(['payment' => function ($query) use ($column_values) {
$query->select($column_values);
}])
;
Here is my attempt to print out the raw query;
$sql = str_replace(['%', '?'], ['%%', "'%s'"], $temp_table_data->toSql());
$fullSql = vsprintf($sql, $temp_table_data->getBindings());
print_r($fullSql);
This is the result;
select * from `selected_postcodes_1434967426_1`
This doesn't look like the right query, I can't work out what Eloquent is doing here. I don't know why the full query is not printing out.
if you have too many result like 1 million, then use offset limit concept. Then it will save you'r time of the query. Also make sure in you select query you are filtering required fields only.( avoid select * from XXXX. use select A, B from XXX).
Related
There is a mysql Person table like below. id is primary, indexed. But other columns are not indexed..
id name surname age city branch
1 John Black 34 London driver
2 Lara Croft 28 New York teacher
3 Ahmad Hasan 41 Doha doctor
...
1000.000......
My Question is when I make execute select query with where clause with multiple conditions, does it decrease select speed.
For example which one is faster?
Select * From Person Where age > 30
or
Select * from Person Where age > 20 AND city = 'London' AND name = 'John' AND branch = 'doctor' AND ...
Could you tell me which one will be faster?
Without indexes, any WHERE clause causes a table scan. That is, to satisfy the query the server must examine every row in the table. So the search operations you have shown take on the order of the same time as one another.
It also takes time to send a large result set from the MySQL server to the client. Fewer rows in the result set make that part of satisfying your query faster.
Pro tip: avoid SELECT * when dealing tables over about 100 rows long. Instead give the names of the columns you actually need.
I actually have a table with 30 columns. In one day this table can get around 3000 new records!
The columns datas look like :
IMG Name Phone etc..
http://www.site.com/images/image.jpg John Smith 123456789 etc..
http://www.site.com/images/image.jpg Smith John 987654321 etc..
I'm looking a way to optimize the size of the table but also the response time of the sql queries. I was thinking of doing something like :
Column1
http://www.site.com/images/image.jpg|John Smith|123456789|etc..
And then via php i would store each value into an array..
Would it be faster ?
Edit
So to take an example of the structure, let's say i have two tables :
package
package_content
Here is the structure of the table package :
id | user_id | package_name | date
Here is the structure of the table package_content :
id | package_id | content_name | content_description | content_price | content_color | etc.. > 30columns
The thing is for each package i can get up to 16rows of content. For example :
id | user_id | package_name | date
260 11 Package 260 2013-7-30 10:05:00
id | package_id | content_name | content_description | content_price | content_color | etc.. > 30columns
1 260 Content 1 Content 1 desc 58 white etc..
2 260 Content 2 Content 2 desc 75 black etc..
3 260 Content 3 Content 3 desc 32 blue etc..
etc...
Then with php i make like that
select * from package
while not EOF {
show package name, date etc..
select * from package_content where package_content.package_id = package.id and package.id = package_id
while not EOF{
show package_content name, desc, price, color etc...
}
}
Would it be faster? Definitely not. If you needed to search by Name or Phone or etc... you'd have to pull those values out of Column1 every time. You'd never be able to optimize those queries, ever.
If you want to make the table smaller it's best to look at splitting some columns off into another table. If you'd like to pursue that option, post the entire structure. But note that the number of columns doesn't affect speed that much. I mean it can, but it's way down on the list of things that will slow you down.
Finally, 3,000 rows per day is about 1 million rows per year. If the database is tolerably well designed, MySQL can handle this easily.
Addendum: partial table structures plus sample query and pseudocode added to question.
The pseudocode shows the package table being queried all at once, then matching package_content rows being queried one at a time. This is a very slow way to go about things; better to use a JOIN:
SELECT
package.id,
user_id,
package_name,
date,
package_content.*
FROM package
INNER JOIN package_content on package.id = package_content.id
WHERE whatever
ORDER BY whatever
That will speed things up right away.
If you're displaying on a web page, be sure to limit results with a WHERE clause - nobody will want to see 1,000 or 3,000 or 1,000,000 packages on a single web page :)
Finally, as I mentioned before, the number of columns isn't a huge worry for query optimization, but...
Having a really wide result row means more data has to go across the wire from MySQL to PHP, and
It isn't likely you'll be able to display 30+ columns of information on a web page without it looking terrible, especially if you're reading lots of rows.
With that in mind, you'll be better of picking specific package_content columns in your query instead of picking them all with a SELECT *.
Don't combine any columns, this is no use and might even be slower in the end.
You should use indexes on a column where you query at. I do have a website with about 30 columns where atm are around 600.000 results. If you use EXPLAIN before a query, you should see if it uses any indexes. If you got a JOIN with 2 values and a WHERE at the same table. You should make a combined index with the 3 columns, in order from JOIN -> WHERE. If you join on the same table, you should see this as a seperate index.
For example:
SELECT p.name, p.id, c.name, c2.name
FROM product p
JOIN category c ON p.cat_id=c.id
JOIN category c2 ON c.parent_id=c2.id AND name='Niels'
WHERE p.filterX='blaat'
You should have an combined index at category
parent_id,name
AND
id (probably the AI)
A index on product
cat_id
filterX
With this easy solution you can optimize queries from NOT DOABLE to 0.10 seconds, or even faster.
If you use MySQL 5.6 you should step over to INNODB because MySQL is better with optimizing JOINS and sub queries. Also MySQL will try to run them into MEMORY which will make it a lot faster aswel. Please keep in mind that backupping INNODB tables might need some extra attention.
You might also think about making MEMORY tables for super fast querieing (you do still need indexes).
You can also optimize by making integers size 4 (4 bytes, not 11 characters). And not always using VARCHAR 255.
I have an issue with a Query I'm conducting to do a search on a Database of events.
The purpose is about sports and the structure is:
id_event event_sport event_city
1 10 153
2 12 270
3 09 135
The table sports is like:
sport_id sport_name
1 Basketball
and the table cities is:
city_id city_name
1 NYC
So things get complicated, because my events table is like:
id_event event_sport event_city
1 10,12 153,270
2 7,14 135,271
3 8,12 143,80
and I have a multi-input search form, so that people can search for events in their city for multiple sports or for multiple cities. I'm using Chosen
The search resultant from Chosen is, for example:
City = 153,270 (if user selected more than one city)
Sport = 12 (if user only selected one sport, can be "9,15")
So what I need is to search for multiple values on cities and sports in the same column, separated by commas, knowing that sometimes we can be searching only for one value, if user didn't input more than one.
My current query is:
SELECT * FROM events e
LEFT JOIN cities c ON e.event_city=c.city_id
LEFT JOIN sports s ON e.event_sport=s.sport_id
WHERE FIND_IN_SET('1CITY', e.event_city) AND FIND_IN_SET('1SPORT', e.event_sport)
;
Which is good to search for one city, but if the user searches for two or more, I don't have way to show it.
Can you please help me?
Thanks in advance.
When the user inputs multiple cities and/or sports, split it on commas, and then the query should look like:
SELECT * FROM events e
LEFT JOIN cities c on e.event_city = c.city_id
LEFT JOIN sports s ON e.event_sport = s.sport_id
WHERE (FIND_IN_SET('$city[0]', e.event_city) OR FIND_IN_SET('$city[1]', e.event_city) OR ...)
AND (FIND_IN_SET('$sport[0]', e.event_sport) OR FIND_IN_SET('$sport[1]', e.event_sport) OR ...)
Using PHP you can build up those OR expressions with:
$city_list = implode(' OR ', array_map(function($x) { return "FIND_IN_SET('$x', e.event_city)"; }, explode(',', $_POST['cities'])));
Do the same to make $sport_list, and then your SQL string would contain:
WHERE ($city_list) AND ($sport_list)
As you can see, this is really convoluted and inefficient, I recommend you normalize your schema as suggested in the comments.
I have a query that outputs address order data:
SELECT ordernumber
, article_description
, article_size_description
, concat(NumberPerBox,' pieces') as contents
, NumberOrdered
FROM customerorder
WHERE customerorder.id = 1;
I would like the above line to be outputted NumberOrders (e.g. 50,000) divided by NumberPerBox e.g. 2,000 = 25 times.
Is there a SQL query that can do this, I'm not against using temporary tables to join against if that's what it takes.
I checked out the previous questions, however the nearest one:
is to be posible in mysql repeat the same result
Only gave answers that give a fixed number of rows, and I need it to be dynamic depending on the value of (NumberOrdered div NumberPerBox).
The result I want is:
Boxnr Ordernr as_description contents NumberOrdered
------+--------------+----------------+-----------+---------------
1 | CORDO1245 | Carrying bags | 2,000 pcs | 50,000
2 | CORDO1245 | Carrying bags | 2,000 pcs | 50,000
....
25 | CORDO1245 | Carrying bags | 2,000 pcs | 50,000
First, let me say that I am more familiar with SQL Server so my answer has a bit of a bias.
Second, I did not test my code sample and it should probably be used as a reference point to start from.
It would appear to me that this situation is a prime candidate for a numbers table. Simply put, it is a table (usually called "Numbers") that is nothing more than a single PK column of integers from 1 to n. Once you've used a Numbers table and aware of how it's used, you'll start finding many uses for it - such as querying for time intervals, string splitting, etc.
That said, here is my untested response to your question:
SELECT
IV.number as Boxnr
,ordernumber
,article_description
,article_size_description
,concat(NumberPerBox,' pieces') as contents
,NumberOrdered
FROM
customerorder
INNER JOIN (
SELECT
Numbers.number
,customerorder.ordernumber
,customerorder.NumberPerBox
FROM
Numbers
INNER JOIN customerorder
ON Numbers.number BETWEEN 1 AND customerorder.NumberOrdered / customerorder.NumberPerBox
WHERE
customerorder.id = 1
) AS IV
ON customerorder.ordernumber = IV.ordernumber
As I said, most of my experience is in SQL Server. I reference http://www.sqlservercentral.com/articles/Advanced+Querying/2547/ (registration required). However, there appears to be quite a few resources available when I search for "SQL numbers table".
Firstly I'd like to start by apologizing for the potentially miss-leading title... I am finding it difficult to describe what I am trying to do here.
With the current project I'm working on, we have setup a 'dynamic' database structure with MySQL that looks something like this.
item_details ( Describes the item_data )
fieldID | fieldValue | fieldCaption
1 | addr1 | Address Line 1
2 | country | Country
item_data
itemID | fieldID | fieldValue
12345 | 1 | Some Random Address
12345 | 2 | United Kingdom
So as you can see, if for example I wanted to lookup the address for the item 12345 I would simply do the statement.
SELECT fieldValue FROM item_data WHERE fieldID=1 and itemID=12345;
But here is where I am stuck... the database is relatively large with around ~80k rows and I am trying to create a set of search functions within PHP.
I would like to be able to perform a query on the result set of a query as quickly as possible...
For example, Search an address name within a certain country... ie: Search for the fieldValue of the results with the same itemID's as the results from the query:
'SELECT itemID from item_data WHERE fieldID=2 and fieldValue='United Kingdom'..
Sorry If I am unclear, I have been struggling with this for the past couple of days...
Cheers
You can do this in a couple of ways. One is to use multiple joins to the item_data table with the fieldID limited to whatever it is you want to get.
SELECT *
FROM
Item i
INNER JOIN item_data country
ON i.itemID = country.itemID
and fieldid = 2
INNER JOIN item_data address
ON i.itemID = country.itemID
and fieldid = 1
WHERE
country.fieldValue= 'United Kingdom'
and address.fieldValue= 'Whatever'
As an aside this structure is often referred to as an Entry Attribute Value or EAV database
Sorry in advance if this sounds patronizing, but (as you suggested) I'm not quite clear what you are asking for.
If you are looking for one query to do the whole thing, you could simply nest them. For your example, pretend there is a table named CACHED with the results of your UK query, and write the query you want against that, but replace CACHED with your UK query.
If the idea is that you have ALREADY done this UK query and want to (re-)use its results, you could save the results to a table in the DB (which may not be practical if there are a large number of queries executed), or save the list of IDs as text and paste that into the subsequent query (...WHERE ID in (...) ... ), which might be OK if your 'cached' query gives you a manageable fraction of the original table.