I have app that uses DB with 50+ tables. Now i'm in situation that i need to install another instance of app. Problem is that i would like to use some tables as "common" data, e.g. "brands" or "cities" or "countries" in both (for now there are only 2, but it might soon be more) apps.
I searched and find that i can make "common" DB with such tables, and have views in each DB instance that points to corresponding table.
Main app queries are heavily relying on that common tables, so i'm concerned if that will slow down my queries since views don't have indexes?
Are there some better practices? I'm looking now for replication in mysql manual. Is that way to go? Replicate tables from common DB to app instance DB's?
Can this be one-direction replication? (only tables in "common" DB can be changed and then replicated to other DB's)?
thanx for advice
Y
Why don't you create Materialized views alias Flexviews then you would create indexes on them and you would not have to worry if it would slow you down.
More on Flexviews at mariadb's site:
Flexviews
Related
I have many queries that use manually created temporary tables in MySQL.
I want to understand if there are any drawbacks associated with this.
I ask this because I use temporary tables for queries that fetch data shown on the home screen of a web application in the form of multiple widgets. In an organization with a significant number of users, this involves creation and deletion of temporary tables numerous times. How does this affect the MySQL Database Server ?
Execution plans can't be optimal when you frequently add/use/remove tables when we would talk about databases in general. As it takes a time to generate an execution plan, the DB is unable to create one when you use described approach.
Is it possible to create a view from tables from two different databases? Like:
creative view 'my_view' as
select names as value
from host_a.db_b.locations
union
select description as value
from host_b.db_b.items;
They currently are different database engines (MyISAM and InnoDB).
thx in advance
Yes, you need to access the remote table via the FEDERATED db engine, then create a view using your query.
However this is a rather messy way to solve the problem - particularly as (from your example query) your data is effectively sharded.
This structure won't allow updates/inserts on the view. Even for an updatable/insertable view, my gut feeling is that you'll run into problems if you try to anything other than auto-commit transactions, particularly as you're mixing table types. I'd recommend looking at replication as a better way to solve the problem.
We have a MySQL database based on InnoDB. We are looking to build an Analytics system for this data. We are thinking to create a cloned database that denormalizes the data to prevent join and uses MyIsam for faster querying. This second database will also facilitate avoiding extra load on the main database to which the data will be written.
Apart from this, we are also creating some extra tables that will store aggregated numbers to avoid recalculation.
I am wondering how can I sync these tables once every day to keep them updated. It looks similar to Master-slave config of MySQL which uses binary log. But in our case, the second database is not an exact slave. Are there any open-source reliable tools or any other ideas which I can use to write an 'update mechanism'?
Thanks in advance.
I have a web site using a database named lets say "site1". I am planning to put another site on the same server which will also use some of the tables from "site1".
So should I use three different databases like "site1" (for first site specific data), "site2" (for second site specific data), and "general" (for common tables). In which there will be join statements between databases general and site1 and site2. Or should I put all tables in one database?
Which is the best practice to do?
How performances differ in each situation?
I am using MySQL. So how is the situation especially for MySQL?
Thanks in advance...
From the performance point of view, there won't be ANY difference. Just keep your indexes in place and you will not notice whether you are using single DB or multiple DBs.
Apart from performance, there are 2 small implications that I can think of:
1. You can not have foreign keys across DBs.
2. Partitioning tables in DB based on their usage or based on applications can help you manage permissions in easy way.
I can speak from recent personal experience. I have some old mysql queries in some PHP code that worked fine with a relatively small database, but as it grew the query got slower and slower.
I have freeradius running mysql in its own database along with another management php app that I wrote. The freeradius table is > 1.5 million rows. I was attempting to join tables from my app's database to the freeradius database. I can say for sure 1.5 million rows is too many. Running some queries locked up my app altogether. I ended up having to re-write portions of my php app to do things differently (ie not joining 2 tables from different database). I also indexed the radius accounting table on some key fields and optimized some queries (mysql EXPLAIN statement is wonderful to help with this). Things are MUCH faster now.
I will definitely be hesitant to join 2 tables from different databases in the future unless really really necessary.
I'm developing a website which to begin with will have three clear sub sites: Forum, News and a Calendar.
Each sub site will have it's own database and common to all of these databases will be a user table which needs to be in each database so that joins can be done.
How can I synchronize all the user tables so that it doesn't matter in which database I make an update, all the databases will have the same user table.
I'm not worried if there is a short sync delay (less than 1min) and I would prefer that the solution was a simple as possible.
Why do the sub-sites need to have their own databases? Can't you just use one database, with separate tables for each of the applications? Or, in PostgreSQL, you could use schemas to the same effect.
Though I would hardly endorse an architecture like this, federated tables may do what you want.
A single app can log into more than one database. While I'd advocate kquinn's answer of "all in one DB", becaue joins will work then, if you really must have separate databases, at least have the user table accessed from one database. "Cloning" a table across multiple databases is fraught with so much peril it's not funny.
I was over complicating the problems/solution.
Since the databases will (for the time being) exist on the same server, I can use a very simple View.