Tetap teratur dengan koleksi
Simpan dan kategorikan konten berdasarkan preferensi Anda.
Halaman ini memberikan ringkasan kontrol konkurensi streaming, seperti jumlah maksimum
tugas pengambilan data perubahan (CDC) serentak dan tugas pengisian ulang. Anda dapat
mengontrol performa streaming dengan meningkatkan atau menurunkan nilai parameter ini.
Ringkasan kontrol konkurensi
Dengan menggunakan kontrol konkurensi, Anda dapat mencapai pengisian ulang dan CDC yang lebih cepat,
atau menyeimbangkan beban di database sumber. Jika memerlukan throughput yang lebih tinggi,
dan dapat menangani beban yang lebih tinggi pada database, Anda dapat meningkatkan konkurensi
tugas CDC dan pengisian ulang. Sebaliknya, jika database Anda mengalami beban
yang tinggi, dan Anda ingin melindunginya agar tidak kelebihan beban, Anda dapat mengurangi
nilai parameter ini.
Jumlah maksimum tugas CDC
Parameter maxConcurrentCdcTasks memungkinkan Anda mengontrol jumlah tugas
CDC yang dijalankan secara paralel oleh streaming. Untuk memperluas throughput CDC, tingkatkan nilai parameter ini dan izinkan Datastream memproses lebih banyak file log CDC secara bersamaan.
Karakteristik utama parameter ini meliputi:
Nilai defaultnya adalah 5. Anda dapat menetapkan parameter ini ke nilai apa pun antara
1 dan 50, inklusif.
Parameter ini hanya berlaku untuk sumber Oracle dan MySQL.
Parameter ini hanya berdampak jika ada lebih banyak file log database yang tersedia
untuk dibaca daripada tugas CDC. Setelan file log dikontrol oleh parameter konfigurasi database sumber: ukuran file log maksimum dan interval waktu rotasi log maksimum. Untuk informasi selengkapnya tentang parameter
ini, lihat dokumentasi Oracle dan MySQL.
Jika Anda mengurangi jumlah tugas CDC serentak, Datastream mungkin
tertinggal di belakang log database, yang pada akhirnya dapat menyebabkan hilangnya posisi log
dan kegagalan streaming.
Jumlah maksimum tugas pengisian ulang
Parameter maxConcurrentBackfillTasks memungkinkan Anda mengontrol jumlah tugas pengisian ulang
yang dapat dijalankan secara paralel oleh aliran data. Anda dapat menaikkan atau menurunkan nilai ini
untuk mengontrol throughput pengisian ulang.
Karakteristik utama parameter ini meliputi:
Nilai defaultnya adalah 15. Anda dapat menetapkan parameter ini ke nilai apa pun antara
1 dan 50, inklusif.
Ada risiko tinggi yang terkait dengan peningkatan konkurensi pengisian ulang,
karena tugas pengisian ulang memiliki dampak signifikan pada performa database.
Setiap tugas pengisian ulang menjalankan kueri SELECT yang tidak difilter pada tabel, dan untuk
tabel besar, kueri tersebut menampilkan banyak baris.
Jika Anda mengurangi konkurensi pengisian ulang, hal ini tidak akan berdampak negatif pada database sumber, kecuali pengisian ulang memerlukan waktu lebih lama untuk diselesaikan.
Mengubah nilai kontrol konkurensi
Anda dapat mengubah nilai parameter kontrol serentak menggunakan
Datastream API.
[[["Mudah dipahami","easyToUnderstand","thumb-up"],["Memecahkan masalah saya","solvedMyProblem","thumb-up"],["Lainnya","otherUp","thumb-up"]],[["Sulit dipahami","hardToUnderstand","thumb-down"],["Informasi atau kode contoh salah","incorrectInformationOrSampleCode","thumb-down"],["Informasi/contoh yang saya butuhkan tidak ada","missingTheInformationSamplesINeed","thumb-down"],["Masalah terjemahan","translationIssue","thumb-down"],["Lainnya","otherDown","thumb-down"]],["Terakhir diperbarui pada 2025-09-04 UTC."],[[["\u003cp\u003eThis page outlines how to manage stream concurrency controls, specifically the maximum number of concurrent Change Data Capture (CDC) and backfill tasks.\u003c/p\u003e\n"],["\u003cp\u003eIncreasing CDC and backfill task concurrency can enhance throughput but may increase load on the source database, while decreasing concurrency can protect the database from overload at the cost of slower performance.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003emaxConcurrentCdcTasks\u003c/code\u003e parameter, applicable to MySQL and Oracle sources only, defaults to 5 and can be adjusted between 1 and 50 to control parallel CDC tasks, with a caution against decreasing it too much as it could cause log position loss.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003emaxConcurrentBackfillTasks\u003c/code\u003e parameter, which also defaults to 15 and ranges from 1 to 50, controls the number of parallel backfill tasks, and while increasing it may significantly impact database performance, decreasing it only extends backfill completion time.\u003c/p\u003e\n"],["\u003cp\u003eConcurrency control parameters can be modified using the Datastream API, as detailed in the documentation for changing the number of concurrent CDC and backfill tasks.\u003c/p\u003e\n"]]],[],null,["# Stream concurrency controls\n\nThis page provides an overview of stream concurrency controls, such as the maximum\nnumber of concurrent change data capture (CDC) tasks and backfill tasks. You can\ncontrol stream performance by increasing or decreasing the values of these parameters.\n\nConcurrency controls overview\n-----------------------------\n\nBy using the concurrency controls, you can either achieve faster backfill and CDC,\nor balance the load on the source database. If you require higher throughputs,\nand can afford a higher load on the database, then you can increase the concurrency\nof CDC and backfill tasks. Conversely, if your database is experiencing a high\nload, and you want to protect it from being overloaded, then you can reduce the\nvalues of these parameters.\n| **Note:** The maximum number of concurrent CDC and backfill tasks parameters are independent of each other. Because of the potential impact that the parameters can have on the source database, we recommend that you modify their values incrementally to see how your system responds.\n\n### Maximum number of CDC tasks\n\n| **Note:** This configuration is only available for MySQL and Oracle sources. CDC in PostgreSQL and SQL Server is single-threaded. For information about how to overcome this limitation for PostgreSQL, see [Diagnose issues](/datastream/docs/diagnose-issues#psql-errors).\n\nThe `maxConcurrentCdcTasks` parameter lets you control the number of CDC\ntasks that a stream runs in parallel. To extend the CDC throughput, increase the\nvalue of this parameter and allow Datastream to process more CDC log files\nat the same time.\n\nThe key characteristics of the parameter include:\n\n- The default value is `5`. You can set this parameter to any value between `1` and `50`, inclusive.\n- The parameter is applicable only to Oracle and MySQL sources.\n- The parameter has impact only if there are more database log files available to read than there are CDC tasks. The log files settings are controlled by the source database configuration parameters: the maximum log file size and the maximum log rotation time interval. For more information about these parameters, refer to Oracle and MySQL documentation.\n- If you decrease the number of concurrent CDC tasks, Datastream might lag behind the database logs, which might eventually lead to log position loss and stream failure.\n\n### Maximum number of backfill tasks\n\nThe `maxConcurrentBackfillTasks` parameter lets you control the number of backfill\ntasks that a stream can run in parallel. You can increase or decrease this value\nto control the backfill throughput.\n\nThe key characteristics of the parameter include:\n\n- The default value is `15`. You can set this parameter to any value between `1` and `50`, inclusive.\n- There is a high risk associated with increasing the backfill concurrency, because backfill tasks have significant impact on the database performance. Each backfill task runs an unfiltered `SELECT` query on a table, and for large tables, such queries return a large number of rows.\n- If you decrease the backfill concurrency, it has no negative impact on the source database except for the backfill taking a longer time to complete.\n\nChange the values of concurrency controls\n-----------------------------------------\n\nYou can change the values of concurrency control parameters using the\nDatastream API.\n\n- To learn how to increase or decrease the number of concurrent CDC tasks, see [Change the number of maximum concurrent CDC tasks](/datastream/docs/manage-streams#change_the_number_of_maximum_concurrent_cdc_tasks).\n- To learn how to increase or decrease the number of concurrent backfill tasks, see [Change the number of maximum concurrent backfill tasks](/datastream/docs/manage-streams#change_the_number_of_maximum_concurrent_backfill_tasks)\n\nWhat's next\n-----------\n\n- See [managing streams](/datastream/docs/manage-streams) to learn more about how to use the Datastream API.\n- See the [Datastream API reference documentation](/datastream/docs/reference/rest/v1/projects.locations.streams) to learn more about the `Stream` resource."]]
