Category Archives: 資料庫

Delete snapshots older than 7 days

Posted on 2023 年 11 月 16 日 by cowman.chiang

To avoid running out of disk space in our test environment, we developed a plan to regularly execute shell scripts to clean up unnecessary snapshots. #!/bin/bash week=`date –date=’7 days ago’ +’%Y%m%d’` echo “list_snapshots” | /home/webuser/hbase-1.2.9/bin/hbase shell | grep “pattern ” … Continue reading →

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HBase Client 2.5.5 in JDK 11

Posted on 2023 年 10 月 02 日 by cowman.chiang

Because of the vulnerability scan results of the project, the JDK version must be upgraded from 8 to 11 to complete the repair. The original HBase Client version 1.2 we used was incompatible with JDK 11, so we had to … Continue reading →

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RocksDB Tool

Posted on 2022 年 10 月 07 日 by cowman.chiang

Install rocksdb first. brew install rocksdb Add alias in zshrc alias ldb = ‘rocksdb_ldb –db=. ‘ List all column families # ldb list_column_families Column families in .: {default, S1, User, C1, C2, U1, C3} Scan command: # ldb –column_family=User scan … Continue reading →

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[HBase] security issue

Posted on 2019 年 03 月 18 日 by cowman.chiang

error message: com.a.b.c.exception.BaseDAOException: org.apache.hadoop.hbase.security.AccessDeniedException: org.apache.hadoop.hbase.security.AccessDeniedException: Insufficient permissions for user ‘Cowman’ (table=ABC, action=READ) in jvm conf. add “-DHADOOP_USER_NAME=webuser”

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[HBase] convert long value to bytes

Posted on 2018 年 11 月 13 日 by cowman.chiang

Java code: public static void main(String[] args) { String stringValue = Bytes.toStringBinary(Bytes.toBytes(1532080782183l)); System.out.println(stringValue); Long longValue = Bytes.toLong(Bytes.toBytesBinary(stringValue)); System.out.println(longValue); } HBase shell command: hbase(main):056:0> Bytes.toStringBinary(Bytes.to_bytes(1532080782183)) => “\\x00\\x00\\x01d\\xB7!{g” hbase(main):057:0> Bytes.toLong(“\x00\x00\x01d\xB7!{g”.to_java_bytes) => 1532080782183

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[HBase] Filters not working for negative integers

Posted on 2018 年 07 月 12 日 by cowman.chiang

[stackoverflow] HBase: Filters not working for negative integers Easility say: Since, Hbase has only BinaryComparators and not other ‘typed’ comparators, it fails to filter on Negative integers as it stores the 2’s compliment of the negative number. Further, the binary … Continue reading →

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[HBase] get the scan result without specific cq

Posted on 2018 年 06 月 06 日 by cowman.chiang

scan ‘TableName’, FILTER=>”QualifierFilter(!=,’binary:QUALIFY2′)”

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Install Hbase 5.9 in Mac OS X

Posted on 2017 年 03 月 10 日 by cowman.chiang

Download hbase package tar.gz file from https://www.cloudera.com/documentation/enterprise/release-notes/topics/cdh_vd_cdh_package_tarball_59.html Untar tar.gz file edit conf/hbase-env.sh export JAVA_HOME={{JAVA_HOME Directory path}} edit conf/hbase-site.xml <property> <name>hbase.rootdir</name> <value>file:///{{location}}/data</value> </property> <property> <name>hbase.zookeeper.property.dataDir</name> <value>{{location}}/zookeeper</value> </property> <property> <name>hbase.zookeeper.quorum</name> <value>{{hostname}}</value> </property> start hbase service bin/start-hbase.sh run hbase shell bin/hbase shell stop … Continue reading →

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HBase: put byte value

Posted on 2016 年 10 月 04 日 by cowman.chiang

put “TableName”, “rowkey”, “cf:fieldname”, [0].pack(“N”) N => byte array put “TableName”, “rowkey”, “cf:fieldname”, [0].pack(“Q>”) Q => 64-bit unsigned, native endian => change endian to big endian

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[MySQL] Find in fixed string

Posted on 2016 年 05 月 27 日 by cowman.chiang

Ref. MySQL 的 FIND_IN_SET函數 SELECT * FROM table WHERE FIND_IN_SET(ID, ‘2,5,6,7,8,9,11,21,33,45’)

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