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Last entries

    20181017.0845
  1. hadoop|CDH > Using Impala through a Proxy for High Availability (HA) - [s]

  2. 20181012.1331
  3. spark2 > What's the meaning of "Locality Level"on Spark cluster - [s]

  4. 20181010.0945
  5. hive > Configuring HiveServer2 High Availability (HS2 HA) with HAProxy - [s]

  6. 20180926.1528
  7. hive > What is vectorization in Hive? - Quora - [s]

    Vectorized query execution Vectorized query execution streamlines operations by processing a block of 1024 rows at a time. Within the block, each column is stored as a vector (an array of a primitive data type). Simple operations like arithmetic and comparisons are done by quickly iterating through the vectors in a tight loop, with no or very few function calls or conditional branches inside the loop. NOTE: https://issues.apache.org/jira/browse/HIVE-11394 adds EXPLAIN VECTORIZATION [ONLY] [SUMMARY|OPERATOR|EXPRESSION|DETAIL]

    20181024.0658
  1. ssltls|https > How to trust self-signed localhost certificates on Firefox - [s]

  2. 20181023.0831
  3. How to rsync over ssh when directory names have space - [s]

    rsync --protect-args # But Mac's rsync doesn't have

  4. 20181018.1213
  5. sqlite > DESC|DESCRIBE|SHOW CREATE TABLE - [s]

    select * from sqlite_master where type='table' and name='personal';

  6. 20181018.0917
  7. java - What are Runtime.getRuntime().totalMemory() and freeMemory()? - Stack Overflow - [s]

    totalMemory() corresponds to the amount of memory currently available to the JVM

  8. 20181017.1628
  9. haproxy > Server X is going DOWN for maintenance (DNS NX status) - [s]

  10. 20181017.1417
  11. PostgreSQL|postgres > replication synchronous - [s]

    synchronous_commit: "on" synchronous_standby_names: "*"

  12. 20181017.1226
  13. excel|bash > SUBTOTAL function for aggregation - [s]

    #declare -A _AGGS; # NOTE: Mac's bash is old so that no associated array local _AGGS_AVERAGE="101" local _AGGS_COUNT="102" local _AGGS_MAX="104" local _AGGS_MIN="103" local _AGGS_STDEV="107" local _AGGS_SUM="109" local _agg_name="" local _agg_num="" if [[ "$_USE_SUBTOTAL" =~ ^(y|Y) ]]; then _agg_name="_AGGS_${_agg}" _agg_num="${!_agg_name}" fi ... if [ -n "${_agg_num}" ]; then printf ",\"=SUBTOTAL(${_agg_num},${_c}${_first_line}:${_c}9999)\"" else printf ",=${_agg}(${_c}${_first_line}:${_c}9999)" fi ...

  14. 20181017.1220
  15. python > Running Multiprocessing in Flask App (not tested) - [s]

  16. 20181017.0950
  17. OSI model > difference between proxy and NAT - [s]

  18. 20181011.1001
  19. Java > Analyse a (one) thread dump with IntelliJ - [s]

  20. 20181010.1126
  21. How to compile, run, and package a Scala project with SBT - [s]

  22. 20181008.1703
  23. PL/pgSQL Cursor with Examples - [s]

  24. 20181008.1029
  25. postgres|postgresql > use "FOR ... IN SELECT" instead of cursor fetch - [s]

    DECLARE v_cursor record; BEGIN FOR v_cursor IN SELECT A.item_cd, A.quantity FROM trx_medical_resep B JOIN trx_resep_data A ON A.medical_resep_seqno = B.medical_resep_seqno WHERE B.medical_resep_seqno = noresep LOOP RAISE NOTICE 'Changes for %', v_curosr; UPDATE inv_pos_item SET quantity = quantity - v_cursor.quantity WHERE item_cd = v_cursor.item_cd AND pos_cd = p_post_cd; END LOOP; END

  26. 20181008.0845
  27. postgresql|potgresql|pgpsql|pg/psql > debug with RAISE NOTICE and to_json - [s]

    Since postgres 9.3 you can use to_json() to convert record into text suitable for notice, RAISE NOTICE '%' to_json(record1);

  28. 20181008.0826
  29. Databases - Practical PostgreSQL - FETCH - [s]

    BEGIN; -- need semicolon DECLARE cur_employee CURSOR FOR SELECT first_name, last_name FROM employees; FETCH FORWARD 2 IN cur_employee;

  30. 20181008.0749
  31. PostgreSQL|postgres|plpgsqlpg/psql > DO execute anonymous code block - [s]

  32. 20181003.1320
  33. java > Introduction to Caffeine (cache|eviction) - [s]

  34. 20181002.1205
  35. postgres > could not write to hash-join temporary file: No space left on device - Stack Overflow - [s]

    SQL> create tablespace temp_tbs location '/some/big/disk'; change temp_tablespaces = 'temp_tbs' in postgresql.conf. select pg_reload_conf();

  36. 20181002.1203
  37. postgres > Tuning Your PostgreSQL Server (pq: out of memory) - [s]

    work_mem If you do a lot of complex sorts, and have a lot of memory, then increasing the work_mem parameter allows PostgreSQL to do larger in-memory sorts which, unsurprisingly, will be faster than disk-based equivalents. This size is applied to each and every sort done by each user, and complex queries can use multiple working memory sort buffers. Set it to 50MB, and have 30 users submitting queries, and you are soon using 1.5GB of real memory. Furthermore, if a query involves doing merge sorts of 8 tables, that requires 8 times work_mem. You need to consider what you set max_connections to in order to size this parameter correctly. This is a setting where data warehouse systems, where users are submitting very large queries, can readily make use of many gigabytes of memory. log_temp_files can be used to log sorts, hashes, and temp files which can be useful in figuring out if sorts are spilling to disk instead of fitting in memory. You can see sorts spilling to disk using EXPLAIN ANALYZE plans as well. For example, if you see a line like Sort Method: external merge Disk: 7526kB in the output of EXPLAIN ANALYZE, a work_mem of at least 8MB would keep the intermediate data in memory and likely improve the query response time.

  38. 20181002.1149
  39. postgres|PostgreSQL > Error: pq: out of memory - [s]

  40. 20180925.1419
  41. Ubuntu > VPN L2TP|L2TPD - [s]

  42. 20180925.1333
  43. Setting up SoftEther VPN Server on Ubuntu 16.04 Xenial Xerus Linux - LinuxConfig.org - [s]

  44. 20180925.1331
  45. Ubuntu 16.04 > VPN|sstp with SoftEther - [s]

    Ref: https://www.softether.org/

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[s] public (23)