I want to create a new table using postgREST, but I was not able to find anything about this in the documentation. Is it possible to create tables? If yes, how?
Sorry if this questions was already asked, but unfortunately I always found solutions for postgres (without t :D)
Thx :)
you can create stored function that creates the table for you, then call that function via postgrest
something like:
create or replace function create_foo_table() returns void as
$$
begin
execute format('create table foo (id int primary key)')
end
$$ language plpgsql;
then call /rpc/create_foo_table in Postgrest
you'd need to reload Postgrest's schema cache after this, in order to read the table: https://postgrest.org/en/v7.0.0/admin.html?highlight=reload#schema-reloading
This likely has security implications, so be careful, especially if using dynamic SQL to create the table
I have 2 external tables in BiqQuery, created on top of JSON files on Google Cloud Storage. The first one is a fact table, the second is errors data - and it might or might not be empty.
I can query each table separately just fine, even an empty one - here is an
empty table query result example
I'm also able to left join them if both of them are not empty.
However, if errors table is empty, my query fails with the following error:
The query specified one or more federated data sources but not all of them were scanned. It usually indicates incorrect uri specification or a 'limit' clause over a union of federated data sources that was satisfied without having to read all sources.
This situation isn't covered anywhere in the docs, and it's not related to this versioning issue - Reading BigQuery federated table as source in Dataflow throws an error
I'd rather avoid converting either of this tables to native, since they are used in just one step of the ETL process, and this data is dropped afterwards. One of them being empty doesn't look like an exceptional situation, since plain select works just fine.
Is some workaround possible?
UPD: raised an issue with Google, waiting for response - https://issuetracker.google.com/issues/145230326
It feels like a bug. One workaround is to use scripting to avoid querying the empty table:
DECLARE is_external_table_empty BOOL DEFAULT
(SELECT 0 = (SELECT COUNT(*) FROM your_external_table));
-- do things differently when is_external_table_empty is true
IF is_external_table_empty = true
THEN ...
ELSE ...
END IF
While creating a table in Athena; it gives me following exception:
no viable alternative at input
hyphens are not allowed in table name.. ( though wizard allows it ) .. Just remove hyphen and it works like a charm
Unfortunately, at the moment the syntax validation error messages are not very descriptive in Athena, this error may mean "almost" any possible syntax errors on the create table statement.
Although this is annoying at the moment you will need to check if the syntax follows the Create table documentation
Some examples are:
Backticks not in place (as already pointed out)
Missing/extra commas (remember that the last column doesn't need the comma after column definition
Missing spaces
More ..
This error generally occurs when the syntax of DDL has some silly errors.There are several answers that explain different errors based on there state.The simple solution to this problem is to patiently look into DDL and verify following points line by line:-
Check for missing commas
Unbalanced `(backtick operator)
Incompatible datatype not supported by HIVE(HIVE DATA TYPES REFERENCE)
Unbalanced comma
Hypen in table name
In my case, it was because of a trailing comma after the last column in the table. For example:
CREATE EXTERNAL TABLE IF NOT EXISTS my_table (
one STRING,
two STRING,
) LOCATION 's3://my-bucket/some/path';
After I removed the comma at the end of two STRING, it worked fine.
My case: it was an external table and the location had a typo (hence didn't exist)
Couple of tips:
Click the "Format query" button so you can spot errors easily
Use the example at the bottom of the documentation - it works - and modify it with your parameters: https://docs.aws.amazon.com/athena/latest/ug/create-table.html
Slashes. Mine was slashes. I had the DDL from Athena, saved as a python string.
WITH SERDEPROPERTIES (
'escapeChar'='\\',
'quoteChar'='\"',
'separatorChar'=',')
was changed to
WITH SERDEPROPERTIES (
'escapeChar'='\',
'quoteChar'='"',
'separatorChar'=',')
And everything fell apart.
Had to make it:
WITH SERDEPROPERTIES (
'escapeChar'='\\\\',
'quoteChar'='\\\"',
'separatorChar'=',')
In my case, it was an extra comma in PARTITIONED BY section,
In my case, I was missing the singlequotes for the S3 URL
In my case, it was that one of the table column names was enclosed in single quotes, as per the AWS documentation :( ('bucket')
As other users have noted, the standard syntax validation error message that Athena provides is not particularly helpful. Thoroughly checking the required DDL syntax (see HIVE data types reference) that other users have mentioned can be pretty tedious since it is fairly extensive.
So, an additional troubleshooting trick is to let AWS's own data parsing engine (AWS Glue) give you a hint about where your DDL may be off. The idea here is to let AWS Glue parse the data using its own internal rules and then show you where you may have made your mistake.
Specifically, here are the steps that worked for me to troubleshoot my DDL statement, which was giving me lots of trouble:
create a data crawler in AWS Glue; AWS and lots of other places go through the very detailed steps this requires so I won't repeat it here
point the crawler to the same data that you wanted (but failed) to upload into Athena
set the crawler output to a table (in an Athena database you've already created)
run the crawler and wait for the table with populated data to be created
find the newly-created table in the Athena Query Editor tab, click on the three vertical dots (...), and select "Generate Create Table DLL":
this will make Athena create the DLL for this table that is guaranteed to be valid (since the table was already created using that DLL)
take a look at this DLL and see if/where/how it differs from the DLL that you originally wrote. Naturally, this automatically-generated DLL will not have the exact choices for the data types that you may find useful, but at least you will know that it is 100% valid
finally, update your DLL based on this new Glue/Athena-generated-DLL, adjusting the column/field names and data types for your particular use case
After searching and following all the good answers here.
My issue was that working in Node.js i needed to remove the optional
ESCAPED BY '\' used in the Row settings to get my query to work. Hope this helps others.
Something that wasn't obvious for me the first time I used the UI is that if you get an error in the create table 'wizard', you can then cancel and there should be the query used that failed written in a new query window, for you to edit and fix.
My database had a hypen, so I added backticks in the query and rerun it.
This happened to me due to having comments in the query.
I realized this was a possibility when I tried the "Format Query" button and it turned the entire thing into almost 1 line, mostly commented out. My guess is that the query parser runs this formatter before sending the query to Athena.
Removed the comments, ran the query, and an angel got its wings!
I have a Borland builder c++ 6 application calling Oracle 10g database. Operating over a LAN. When the application in question makes a simple db select e.g.
select table_name from element_tablenames where element_id = 10023842
the following is recorded as happening in Oracle (from the performance logs)
select table_name
from element_tablenames
where element_id = 10023842
then immediately (and not from C++ source code but perhaps deeper)
select table_name, element_tablenames.ROWID
from element_tablenames
where element_id = 10023842
The select statement is only called once in the TADODbQuery object, yet two queries are being performed - one to parse and the other adds the ROWID for executon.
Over a WAN and many, many queries this is obviously a problem to the user.
Does anyone know why this might be happening, can someone suggest a solution?
Agree with Robert.
The ROWID uniquely identifies a row in a table so that the returned record can be applied back to the database with any changes (or as a DELETE).
Is there a way to identify a particular column (or set of columns) as a primary key so that it can be used to identify a row without using a ROWID.
I don't know exactly where the RowID is coming from, it could be either the TAdoQuery implementation or the Oracle Driver. But I am sure I found the reason.
From the Oracle docs:
If the database table does not contain a primary key, the ROWID must be selected explicitly when populating DataTable.
So I suspect your Table does not have a primary key, either add one or add the rowid.
Either way this will solve the duplicate query problem.
Since you are concerned about performance. In general
Using TAdoQuery you can set the CursorType to optimize different behaviors for performance. This article covers this from a TAdoQuery perspective. MSDN also has an article that covers it from from a general ADO Perspective. Finally the specifications from the Oracle Driver can be useful.
I would recommend setting the Cursor to either as they are the only supported by Oracle
ctStatic - Bi-directional query produced.
ctOpenForwardOnly - Unidirectional query produced, fastest but can't call Prior
You can also play with CursorLocation to see how it effects your speed.
I was wondering what the "best" way to verify the structure of my database is with SQLite in Qt / C++. I'm using SQLite so there is a file which contains my database, and I want to make sure that, when launching the program, the database is structured the way it should be- i.e., it has X tables each with their own Y columns, appropriately named, etc. Could someone point my in the right direction? Thanks so much!
You can get a list of all the tables in the database with this query:
select tbl_name from sqlite_master;
And then for each table returned, run this query to get column information
pragma table_info(my_table);
For the pragma, each row of the result set will contain: a column index, the column name, the column's type affinity, whether the column may be NULL, and the column's default value.
(I'm assuming here that you know how to run SQL queries against your database in the SQLite C interface.)
If you have QT and thus QtSql at hand, you can also use the QSqlDatabase::tables() (API doc) method to get the tables and QSqlDatabase::record(tablename) to get the field names. It can also give you the primary key(s), but for further details you will have to follow pkh's advice to use the table_info pragma.