As I advanced in the title, I would like to make queries directly against my database, instead of using the URL get service provided by Nominatim.
I have my own Nominatim instance running in a Debian machine, and is supposed I'm working over up-to-date versions.
The thing is that I would like to test multiple nodes at the same time in order to get common information or relations between them. As I gave hundreds of tables in my Nominatim db, and doesn't look like querying them is trivial at all, I'm asking for some ideas.
At the end, I will probably just use the tool over way's nodes, so maybe there is a trick or some specific tables where I can match them.
Related
I have one machine on which several applications are hosted. Applications work on separated data and don't interact - each application only needs access to its own data. I want to use PostgreSQL as RDBMS. Which one of the following is best and why?
One global Postgres sever, one global database, one schema per application.
One global Postgres server, one database per application.
One Postgres server per application.
Feel free to suggest additional architectures if you think they would be better than the ones above.
The questions you need to ask yourself: does any application ever need to access data from another application (in the same SQL statement). If you can can answer that with a clear NO, then you should at least go for separate databases. Cross-database queries aren't that straight-forward in Postgres, so if the different applications do need a lot of data from other applications, then solution 1 might be deployment layout to think about. If this would only concern very few tables, then using foreign data wrappers with different databases might still be a better solution.
Solution 2 and 3 are more or less the same from the perspective of each application. One thing to keep in mind when deciding between 2 and 3 is availability. Some configuration changes to Postgres require a restart of the service. Is an outage of all applications acceptable in that case, even though the change was only necessary for one?
But you can always start with option 2 and then move database to different servers later.
Another question to ask is if all applications always use the same (major) Postgres version With solution 2 you must make sure that all applications are compatible with a new Postgres version if one of them wants to upgrade e.g. because of new features that the application wants to use.
Solution 1 is stupid : a SQL schema is not a database. Use SQL schema for one application that have multiple "parts" like "Poduction", "sales", "marketing", "finances"...
While the final volume of the data won't be too heavy and the number of user won't be too much, use only one PG cluster to facilitate administration tasks
If the volume of data or the number of user increases, it will be time to separates your different databases on new distinct PG clusters....
We recently migrated a large DB2 database to a new server. It got trimmed a lot in the migration, for instance 10 years of data chopped down to 3, to name a few. But now I find that I need certain data from the old server until after tax season.
How can I run a UNION query in DBeaver that pulls data from two different connections..? What's the proper syntax of the table identifiers in the FROM and JOIN keywords..?
I use DBeaver for my regular SQL work, and I cannot determine how to span a UNION query across two different connections. However, I also use Microsoft Access, and I easily did it there with two Pass-Through queries that are fed to a native Microsoft Access union query.
But how to do it in DBeaver..? I can't understand how to use two connections at the same time.
For instance, here are my connections:
And I need something like this...
SELECT *
FROM ASP7.F_CERTOB.LDHIST
UNION
SELECT *
FROM OLD.VIPDTAB.LDHIST
...but I get the following error, to which I say "No kidding! That's what I want!", lol... =-)
SQL Error [56023]: [SQL0512] Statement references objects in multiple databases.
How can this be done..?
This is not a feature of DBeaver. DBeaver can only access the data that the DB gives it, and this is restricted to a single connection at a time (save for import/export operations). This feature is being considered for development, so keep an eye out for this answer to be outdated sometime in 2019.
You can export data from your OLD database and import it into ASP7 using DBeaver (although vendor tools for this are typically more efficient for this). Then you can do your union as suggested.
Many RDBMS offer a way to logically access foreign databases as if they were local, in which case DBeaver would then be able to access the data from the OLD database (as far as DBeaver is concerned in this situation, all the data is coming from a single connection). In Postgres, for example, one can use a foreign data wrapper to access foreign data.
I'm not familiar with DB2, but a quick Google search suggests that you can set up foreign connections within DB2 using nicknames or three-part-names.
If you check this github issue:
https://github.com/dbeaver/dbeaver/issues/3605
The way to solve this is to create a task and execute it in different connections:
https://github.com/dbeaver/dbeaver/issues/3605#issuecomment-590405154
I have a collection in db(e.g. merchants) which gets updated regularly in prod.
What we have is a db population script that we run every time.
This removes configuration collections and inserts them again based on data in script e.g. includes the update to a merchant config.
db.merchants.remove({});
db.merchants.insert(themerchant);
Is there a better pattern/procedure that people use to do this?
I cant seem to find guidance on how people are doing this in production. Links to methods people use would be great.
E.g. In SQL Server we create patches
https://data.stackexchange.com/ lets me query some (all?) of
stackexchange's data/tables using arbitrary SQL queries, including
parametrization.
What program do they use to do this and is it published?
I want to create something like this myself (different data), but am
constantly worried that I'll miss an injection attack or set
permissions incorrectly.
Obviously, data.stackexchange.com has figured out how to do this
securely. How do I replicate what they've done?
This follows up my earlier question: Existing solution to share database data usefully but safely?
Let me start by saying, what I know about Pentaho wouldn't fill up a single paragraph. I'm more knowledgeable about PostgreSQL. I'm working with some contractors that are building a set of monthly reports in Pentaho (v. 4.5) for my company. Some of the data needs to go through a ETL process and get rolled up for reporting purposes. From a dba(ish) point of view, I would like to move these tables into a separate PostgreSQL schema.
I know that Pentaho is often times used with MySQL (which doesn't have schemas) and I'm concerned this might cause problems. I've done some "googlin'" and I don't turn up a lot of hits on the topic, but I did find a closed bug from a few years ago - thus implying that the functionality should be supported.
before I do this, I would like to see if anyone knows of a reason this will fail or be a bad idea. (or if you've done it an it works great, please let me know that, too).
Final notes: I'm using PostgreSQL 9.1.5, and I don't have access to a Pentaho instance to even test this myself. And I'm hoping the good folks in the Stackoverflow community will share their expertise and save me from having to install one and the hours of playing/testing to get an idea of this is a bad idea.
EDIT:
I sort of knew this question was a bit vague, but I was hoping that some one would read it and share any experience they have. So, Let me spell it out more clearly and ask more explicit questions.
I have not done anything. I don't know Pentaho. I don't want to learn Pentaho (not that there is anything wrong with Pentaho... It's just not where my interests are right now). My company hired contractors (I did not hire them). They have experience with Pentaho, but with MySQL. They don't really know anything about PostgreSQL. There are some important difference between PostgreSQL and MySQL. Including the fact that PostgreSQL supports schemas (whereas MySQL uses separate database... similar in concept be behave differently in some ways). Some ORMs (and tools) don't really like this... for example, the Django framework still doesn't really fully support schemas in Postgresql (I know this because I use Python and Django often and my life is much better when I keep things in the "public" schema). Because of my experience with Django and PostgreSQL schemas, I'm a bit leery of moving this data to a new schema.
I do understand that where ever the tables are, they will need permissions to be able to access the data.
My explicit questions:
Do you use Pentaho to access a PostgreSQL database to access tables in schemas other than "public" (the default).
If so, does it just work (no problems)?
If you had problems, would you please be willing to share with me (and the Stackoverflow community) any online resources that helped you? Or would you be willing to detail what you remember here?
Do you know of anything that just won't work correctly? For example, an open bug in Pentaho related to this topic.
Again, it's not your standard kind of question. I'm hoping that someone out there has experience and is willing to share it here and save me from having to spend time setting up a new Pentaho instance and trying to learn Pentaho well enough to test it, etc.
Thanks.
Two paths you can take:
1) What previous post said ("Pentaho steps (table inputs, outputs, etc.) usually allow you to specify a database schema.")
2) In database connection, advanced tab, "The preferred schema name".
If you're working with different schemas, you can create one database connection per schema. With this approach you can leave schema field in input/output steps empty.
We use MS SQL server and I can tell you that Pentaho does struggle with the idea of a schema. Many of their apps allow you to select a schema but Pentaho, like you said, is built to use something like mySQL.
Make you pentaho database user work like it would be working in mySQL.
We made the database user default to dbo then we structured our tables like dbo.dimDimension,
dbo.factFactTable etc. Basically, only use dbo for Pentaho purposes. (Or whatever schema you want to default to.)
I use PDI and PgSQL extensively every day with a bunch of different schemas. It works fine. The only trouble you might run into is Pg's troublesome practice of forcing unquoted identifiers to lower instead of upper case. I soon realized everything was easier when I set the Advanced connection property to "Quote all in database".
Yes, you have to quote everything when you type SQL if PDI doesn't do it for you, but it works quite well. Haven't experimented with forcing all identifiers to lower case, but I expect that would work as well.
And yes, use the "Preferred schema nanme" as well, but be aware that some steps use that option and others don't. You can't, for example, expect it to add schema names to SQL you type into a Table Input step.
The only other issues you might run into are the limits of Pg's JDBC driver. It's not as good as SQL Server's or DB2's, but the only thing I've every had trouble with was sending error rows from a Table Output step to another step when the Table Output step was in batch mode.
Have fun learning PDI. It makes a great complement to your DBA skills.
Brian
Pentaho steps (table inputs, outputs, etc.) usually allow you to specify a database schema.
I did a quick test using PDI and our 8.4 Postgres instance and was able to explore, read from and write to tables in different schemas.
So, I think this is a reasonable direction. Hope this helps.