This article will show you how you can create a synchronization of LDAP groups with Roles and Users in the Database
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This article explains the information found in EXA_ALL_OBJECT_SIZES
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Generally speaking, NULL is not a special value, but it represents an undefined value. This article describes how to work with NULL values and the types of valid comparisons
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This article talks about using DECIMAL datatype to achieve more stringent results than DOUBLE datatype.
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As Exasol only supports the transaction isolation level "SERIALIZABLE", this article looks at transactions and potential transaction conflicts.
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MERGE is designed to use a small UPDATE table to affect a larger FACT table. This article explains how it works
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Problem To reproduce certain problems, Exasol support may ask you to send DDL statements for required tables and views. At this point you have two choices: Start drilling around to find each and every required view / table etc. This may be a lot of work and may end up with some communication round trips in case you overlooked a dependency or two. Skip all that and just send us the full DDL for all schemas in your database instance. Just let us sort out what is needed and what is not. Both options are not optimal. Solution The attachment of this article contains a procedure script (Lua) that can create DDL statements for recursive dependencies of a view. The DDL are presented as a single-column result-set and are ready for copy/paste into a text editor (or EXAplus) for saving. Example Call Script call execute script meta.create_DDL( 'DUT' , 'TRUNK' ); Example output --DDL created by user SYS at 2017-11-14 09:44:59.554000 --========================================-- -- table dependencies -- --========================================-- CREATE SCHEMA "DUT"; CREATE TABLE "DUT"."TAB1"( "I" DECIMAL(18,0) IDENTITY NOT NULL, "J" DECIMAL(3,0) ); -- SYSTEM TABLE: SYS.EXA_METADATA --========================================-- -- function dependencies -- --========================================-- function func( param decimal(3) ) returns decimal(3) as begin return sqrt(param) * (select max(i) from dut.tab1); end / --========================================-- -- script dependencies -- --========================================-- CREATE LUA SCALAR SCRIPT "LUA_SCALAR" () RETURNS DECIMAL(18,0) AS function run() return decimal(10,18,0) end / --========================================-- -- view dependencies -- --========================================-- --> level 2 -- SYSTEM VIEW: SYS.CAT --> level 1 CREATE VIEW "DUT"."BRANCH" as ( select * from exa_metadata, cat ); -- final query/view: CREATE VIEW "DUT"."TRUNK" as ( select * from dut.tab1, dut.branch where func(j) > lua_scalar() ); Caution This script is work in progress and has only seen minimal testing so far. Things known not to work: Virtual Schemas – It is unlikely we would be able to clone your remote system anyway. Connections and IMPORT inside views – Like virtual schemas, it probably does not make much sense. Dependencies inside scripts – This is branded 'dynamic SQL' and our engine can not determine those dependencies without actually executing the script with specific input. SELECT dependencies inside functions – Just don't do that. Like with scripts, these dependencies to not show up in the system. If your model contains any of the above and it turns out to be relevant for reproduction of a problem, you might have to revert to "Skip all that" above. The "Copy Database" script in create-ddl-for-the-entire-database   may be of use then. Additional References https://www.exasol.com/support/browse/IDEA-359 https://community.exasol.com/t5/database-features/create-ddl-for-the-entire-database/ta-p/1417
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NULL and nil have two different meanings in the context of Lua Programming. This article explains the difference
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This article describes how Unicode is supported in Exasol
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Questions What data can you read using subconnections? What data can you insert using subconnections? How to establish parallel connections? What about transactions in parallel mode? What about transactions in parallel mode? Answer You can use subconnections to read or insert data in parallel from and into the EXASOL server. This will increase performance considerably. Using this interface you can read/write data in parallel from different physical hosts or from different processes or in one process from different threads. What data can you read using subconnections? You need a statement that produces a large result set. The result set can be then retrieved in parts from the parallel connections. For small results this interface has no advantage. What data can you insert using subconnections? Like when reading data, using this interfaces only makes sense if you want to insert large amounts of data. You can simply insert rows into a table in EXASOL using a prepared insert statement. The data coming through the parallel connections will be put together by the server into the right table. How to establish parallel connections? First you need a normal JDBC connection. On this you can use the method   EnterParallel()   to start operating with subconnections. You will receive connection strings for all new parallel connections you can start now. Start the subconnections with auto commit off. After this you can start reading or sending data, nearly like in a normal connection. Attention: You can specify the maximum number of subconnections in   EnterParallel() . This number may be reduced by the server because only one subconnection is allowed per database node. You have to establish the subconnections by using all connection strings received from   Get Worker Hosts() . Subconnections can only be used after all connections have been established. What about transactions in parallel mode? Start the subconnections with auto commit off. Commits should be made only on the main connection after the subconections have inserted all data and they have closed the prepared statements. An Java example is attached. In the example a main connection reads the connection strings for the subconnections from the server. For each subconnection a thread is started that inserts a few rows. Commit is executed on the main connection. Then other threads read the data from the table.
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In Exasol, the data is automatically evenly distributed among each node. This distribution is random, however.  By specifying distribution keys, you can control how the data is distributed, which can lead to enormous performance improvements. 
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This article describes the difference between local and global joins, and how to convert them. 
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This article give suggestions on how to minimize transaction conflicts.
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This article describes how you convert Exasol's GEOMETRY types to GeoJSON
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If you want to implement Column Level Security in addition to Row Level Security, this example shows you how this can work using Virtual Schemas
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This article provides steps to manage session-level use of resources when there are a high number of sessions attached to Exasol.
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Estimating work duration when doing reorganizations within Exasol.
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Tips on how to improve joins within Exasol.
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SQL statement to add locking information to your session system tables using the EXA_SQL_LAST_DAY statistics.
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This article gives general information about Exasol's indices.
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