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  1. CUBRID INTERNAL: CUBRID Double Write Buffer

    Written by MyungGyu Kim on 03/08/2022 INTRODUCTION Data in the database is allocated from disk to memory, some data is read and then modified, and some data is newly created and allocated to memory. Such data should eventually be stored on disk to ensure that it is permanently stored. In this article, we will introduce one of the methods of storing data on disk in CUBRID to help you understand the CUBRID database. The current version at the time of writing is CUBRID 11.2. DOUBLE WRITE BUFFER First of all, I would like to give a general description of the definition, purpose, and mechanism of Double Write Buffer. What is Double Write Buffer? By default, CUBRID stores data on disk through Double Write Buffer. Double Write Buffer is a buffer area composed of both memory and disk. By default, t...
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  2. Monitoring CUBRID through Scouter

    Written by TaeHwan Seo on 01/18/2022 CUBRID users can monitor items in CUBRID through the Scouter. It was developed based on CUBRID 11.0 version. Full features are available from CUBRID 10.2.1 Version. Scouter (Server, Client) is available from version 2.15.0, bug fixes and features will be added by participating in Scouter GitHub in the future. The latest version of Scouter (as in 2022.01.18) is Scouter 2.15.0, Multi Agent support and bug fixes are currently in the PR stage. 1. What is Scouter? Scouter is an Open Source Application Performance Management (APM), it provides monitoring function for applications and OS. Scouter Basic Configuration Scouter-provided Information ​- WAS Basic Information Response speed/profiling information for each request, number of server requests/number of re...
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  3. QUERY CACHE Hint

    Written by MinJong Kim on 12/09/2021 ABOUT QUERY CACHE With the release of CUBRID 11.0, the CUBRID DBMS supports QUERY CACHE hint. In this article, we will take some time to look at QUERY CACHE. 1. What is Query Cache? Query Cache is a DBMS feature that stores the statements together with the retrieved record set in memory using the SELECT query statement and returns the previously cached values when the identical query statement is requested. The query cache can be useful in an environment where you have tables that do not change very often and for which the server receives many identical queries. Queries using the QUERY_CACHE hint are cached in a dedicated memory area, and the results are also cached in separate disk space. Query Cache Features 1. The QUERY_CACHE hint only applies to SELE...
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  4. CUBRID INSIDE: HASH SCAN Method

    Written by SeHun Park on 11/09/2021 - HASH SCAN Hash Scan is a scan method for hash join. Hash Scan is applied in view or hierarchical query. When a subquery such as view is joined as inner, index scan cannot be used. In this case, performance degradation occurs due to repeated inquiry of a lot of data. In this situation, Hash Scan is used. The picture above shows the difference between Nested Loop join and Hash Scan in the absence of an index. In the case of NL join, the entire data of INNER is scanned as many as the number of rows of OUTER. In contrast, Hash Scan scans INNER data once when building a hash data structure and scans OUTER once when searching. Therefore, you can search for the desired data relatively very quickly. Here, the internal structure of Hash Scan is written as the fl...
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  5. Converting PL/SQL to CUBRID Java SP using ANTLR and StringTemplate

    Written by Youngjin Joo on 09/30/2021 CUBRID DBMS (hereinafter 'CUBRID') does not support PL/SQL. If you want to continue your project by creating functions or subprograms with PL/SQL syntax in CUBRID, you need to convert them to Java Stored Function/Procedure (hereinafter 'Java SP'). Database developers, administrators, and engineers are often familiar with PL/SQL syntax but not with programming languages. In addition, application development depends very little on the DBMS used, but converting PL/SQL to Java SP seems difficult because it feels like you're developing a new system. Therefore, while I am looking for an easy way to convert PL/SQL to Java SP, I found out about ANTLR. ANTLR is a tool for generating parsers. With the help of contributors around the world, ANT...
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