We created a temporary table (in memory) through spark.
When we sftp to the server and use beeline, we can query on the this temporary table like "select * from Table1" without issue.
However, when we use GUI tool with corresponding driver on local machine (the connection string is "jdbc:spark://servername:port/default" ), we have trouble. We can see the temporary table Table1 by using "show tables;" in the GUI tool. However, when we try to use "select * from Table1" in the tool, It shows an error "[Simba]JSQLEngine The table "Table1" could not be found., SQL state: HY000, Query: select * from Table1. [SQL State=HY000, DB Errorcode=500051]". Note that we are using the trial version of the Simba JDBC driver for testing.
Also, I tried hive-jdbc driver from cloudra using connection string "jdbc:hive2://servername:port/default". It is the same issue. Please help. Thanks a lot.
It turns out that some of the drivers requires a "limit" clause after the select. Once I add that, it retrieved data.
Related
I have some queries against a Sybase database that after some changes in our Java (JDBC) code are failing to execute because the database is returning an error message where it demands we provide the owner in front of the table name but that is something I would prefer to provide in a single place in our configuration. We are using ASE 16.
For example, we had a query like "SELECT * FROM table_name" that will not work anymore unless we specify "SELECT * FROM database_name..table_name"
I think there should be a simple answer for this but I am struggling to find one, thank you in advance.
I have written a program using pyspark to connect to oracle database and fetch data. Below command works fine and returns the contents of the table:
sqlContext.read.format("jdbc")
.option("url","jdbc:oracle:thin:user/password#dbserver:port/dbname")
.option("dbtable","SCHEMA.TABLE")
.option("driver","oracle.jdbc.driver.OracleDriver")
.load().show()
Now I do not want to load the entire table data. I want to load selected records. Can I specify select query as part of this command? If yes how?
Note: I can use dataframe and execute select query on the top of it but I do not want to do it. Please help!!
You can use subquery in dbtable option
.option("dbtable", "(SELECT * FROM tableName) AS tmp where x = 1")
Here is similar question, but about MySQL
In general, the optimizer SHOULD be able to push down any relevant select and where elements so if you now do df.select("a","b","c").where("d<10") then in general this should be pushed down to oracle. You can check it by doing df.explain(true) on the final dataframe.
I'm attempting to query a proprietary RDBMS using Apache Drill. I've created the plugin as a JDBC data source and put my JDBC jar in the jars/3rdparty directory, and I'm able to successfully run a query such as SELECT * FROM mytable.
However, if I use a column name in the query such as SELECT mycol FROM mytable, Drill returns the following error: Error: VALIDATION ERROR: From line 1, column 8 to line 1, column 9: Column 'mycol' not found in any table. Moreover, I've noticed that my schema is entirely missing if I run SELECT * FROM INFORMATION_SCHEMA.SCHEMATA, so I have a hunch that Drill is unable to retrieve my database schema from the JDBC driver.
I'm wondering what method of the JDBC driver may be implemented incorrectly that's causing this problem. The JDBC driver has been used with other 3rd party software such as Spark with no issue.
In order to perform a query on your table you need to prefix the name of your table with the name you gave your storage plugin. For example if you named your storage plugin rdbms your query should look like this:
SELECT * FROM rdbms.mytable
Your additional query SELECT * FROM INFORMATION_SCHEMA.SCHEMATA likely failed for the same reason. Try SELECT * FROM rdbms.INFORMATION_SCHEMA.SCHEMATA. And don't forget to replace rdbms with the name you gave your storage plugin.
I think we should query on drill like select * from dfs.<storagePlugin>.tableName
Can you check once.?
I'd like to know what is my RAC cluster name using SQL query. I've found out that it can be retrieved using Oracle tool cemutlo -n or just ocrdump (see http://www.br8dba.com/tag/how-to-display-oracle-cluster-name/). However, it's not possible in this case, because on target environment, I can only execute SQL queries and I don't have access to DBMS installation directory.
I've found out (here https://community.oracle.com/thread/2510788?tstart=0) that it can be done using some unusual queries:
SELECT a.ID, a.CLUSTER_ID FROM TABLE(DBMS_DATA_MINING.GET_MODEL_DETAILS_OC('CLUS_OC_1_15',NULL,NULL,1,0,0)) a
select * from table(dbms_data_mining.get_model_details_km('CLUS_KM_1_25'))
However, they don't work on my environment and I'm unable to create new model.
Most preferably, I'd just read this from some kind of v$/gv$ tables - but I can't find it there. I guess that's because cluster is far below DBMS.
Finally, I found out that there is no way to do that :(.
I am using Oracle 11g and Toad for Oracle. How can I display execution plan for queries?
In Sql server management studio execution plan can be displayed as graphical format. Is there any functionality/tool like that on Toad for oracle?
CTRL-E
Make sure you've ended the query with a semi-colon (and the query above)
Edit:
You need to set-up the TOAD plan table for use. If you think it's already setup on your DB then you may just need to be granted access. Alternatively in my slightly older version of TOAD it's under:
Database --> Administer --> Server Side Objects Wizard. From here you can create the plan table(s) in a schema that you choose.
You should create the PLAN_TABLE using a script provided by Oracle
which is named UTLXPLAN.SQL and is located in one of the installation folders
on the database server.
Then, you should use the EXPLAIN PLAN statement for generating a plan for a SQL statement, like this:
EXPLAIN PLAN SET STATEMENT_ID = 'your_identifier_for_this_plan'
FOR
... your statement ... ;
Then, you can use either a select from PLAN_TABLE (usually using a hierarchical query) or the DBMS_XPLAN.DISPLAY_PLAN procedure to display the plan.
In the same folder where the UTLXPLAN.SQL file is located, there usually exist
examples of using this procedure.
Also, in SQL*PLUS you can use the SET AUTOTRACE feature.
For TOAD FOR ORACLE
this helped me How do I view the Explain Plan in Oracle Sql developer?, I just write what they did in sql developer and wrote in the toad editor and then execute.
Example
explain plan for select field1, field2 from TABLE_NAME;
SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY);
Check that all queries end with a semicolon, put the cursor on the query you want to analyze and hit CTRL-E.
The first time you could get a popup that asks for the name of the plan table, it suggests TOAD_PLAN_TABLE but it's better to use the standard Oracle table PLAN_TABLE that should be already available. So enter PLAN_TABLE in place of TOAD_PLAN_TABLE (do not specify a schema) and hit OK. You should get a message saying that the object already exists: hit OK again to acknowledge it. Now try CTRL-E again and you'll get the explain plan.
To view/change the currently configured plan table name go to menu "View / Toad Options / Oracle General".