"Monitor: High disk read" 在对 virtuoso 本地端点执行查询时

Question

我有一个本地 Virtuoso 端点，我正在使用 Python 查询它（查询非常复杂）。一段时间后，脚本执行变慢并开始显示 Monitor: High disk read (1)。

这是 Virtuoso 日志：

14:43:16 { Loading plugin 1: Type `plain', file `wikiv' in `/home/bilal/git/virtuoso/lib/virtuoso/hosting'
14:43:16   WikiV version 0.6 from OpenLink Software
14:43:16   Support functions for WikiV collaboration tool
14:43:16   SUCCESS plugin 1: loaded from /home/bilal/git/virtuoso/lib/virtuoso/hosting/wikiv.so }
14:43:16 { Loading plugin 2: Type `plain', file `mediawiki' in `/home/bilal/git/virtuoso/lib/virtuoso/hosting'
14:43:16   MediaWiki version 0.1 from OpenLink Software
14:43:16   Support functions for MediaWiki collaboration tool
14:43:16   SUCCESS plugin 2: loaded from /home/bilal/git/virtuoso/lib/virtuoso/hosting/mediawiki.so }
14:43:16 { Loading plugin 3: Type `plain', file `creolewiki' in `/home/bilal/git/virtuoso/lib/virtuoso/hosting'
14:43:16   CreoleWiki version 0.1 from OpenLink Software
14:43:16   Support functions for CreoleWiki collaboration tool
14:43:16   SUCCESS plugin 3: loaded from /home/bilal/git/virtuoso/lib/virtuoso/hosting/creolewiki.so }
14:43:16 OpenLink Virtuoso Universal Server
14:43:16 Version 07.20.3229-pthreads for Linux as of Sep  4 2018
14:43:16 uses parts of OpenSSL, PCRE, Html Tidy
14:43:16 Database version 3126
14:43:16 SQL Optimizer enabled (max 1000 layouts)
14:43:17 Compiler unit is timed at 0.000097 msec
14:43:19 Roll forward started
14:43:19     77 transactions, 6771 bytes replayed (100 %)
14:43:19 Roll forward complete
14:43:20 Checkpoint started
14:43:20 Checkpoint finished, log reused
14:43:22 HTTP/WebDAV server online at 8890
14:43:22 Server online at 1111 (pid 3556)
14:51:30 * Monitor: High disk read (1)
14:54:07 * Monitor: High disk read (1)
14:56:08 * Monitor: High disk read (1)

过了一会儿，我收到磁盘 space 警告，因为 virtuoso/var/lib/virtuoso/db 中有一个名为 virtuoso-temp.db 的文件。

我不知道到底发生了什么，我知道这是一个资源问题，但我认为我正在查询的数据库并不需要那么多。

原始海龟文件大小为 4.5 Gb。
内存：32Gb
CPU i5 7th Gen 3.40GHz × 4

Answer 1

执行需要比可用更多的 RAM 和临时磁盘存储空间，因为

the problem was in the query, it had a lot of OPTIONAL(s)

"Monitor: High disk read" 在对 virtuoso 本地端点执行查询时

"Monitor: High disk read" while executing query against virtuoso local endpoint

virtuoso