{"id":79,"date":"2026-01-28T16:45:05","date_gmt":"2026-01-28T08:45:05","guid":{"rendered":"https:\/\/yuriblog.online\/?p=79"},"modified":"2026-01-28T16:45:06","modified_gmt":"2026-01-28T08:45:06","slug":"oracle%e5%a4%a7lob%e6%b8%85%e7%90%86","status":"publish","type":"post","link":"https:\/\/yuriblog.online\/index.php\/2026\/01\/28\/oracle%e5%a4%a7lob%e6%b8%85%e7%90%86\/","title":{"rendered":"oracle\u5927lob\u6e05\u7406"},"content":{"rendered":"\n<p id=\"ub3ec0bc8\">\u7ed3\u8bba\uff1a\u5927lob\u53ea\u80fd\u901a\u8fc7truncate\u6216\u5f00\u542f\u884c\u79fb\u52a8\u540edelete\u7684\u65b9\u5f0f\u6e05\u7406<\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"nQYsz\">1.\u5148\u660e\u786e\uff1aLOB \u5b57\u6bb5\u7684\u5b58\u50a8\u672c\u8d28<\/h3>\n\n\n\n<p id=\"u8af5c697\">Oracle \u4e2d LOB\uff0c\u5206\u4e24\u79cd\u5b58\u50a8\u65b9\u5f0f \u6838\u5fc3\u662f<strong>LOB \u6bb5\u4e0e\u8868\u6bb5\u5206\u79bb<\/strong><\/p>\n\n\n\n<p id=\"u2fdea657\"><strong>\u5185\u8054 LOB\uff08INLINE\uff09\uff1a<\/strong>\u5c0f LOB\uff08\u9ed8\u8ba4 &lt; 4000 \u5b57\u8282\uff09\u76f4\u63a5\u5b58\u5728\u8868\u7684\u884c\u6570\u636e\u5757\u4e2d\uff0c\u4e0e\u666e\u901a\u5b57\u6bb5\u65e0\u672c\u8d28\u533a\u522b\uff1b<\/p>\n\n\n\n<p id=\"u747a0875\"><strong>\u5916\u8054 LOB\uff08OUT OF LINE\uff09<\/strong>\uff1a\u5927 LOB\uff08\u8d85\u8fc7\u9608\u503c\uff09\u4f1a\u5728\u8868\u6bb5\u5916\u5355\u72ec\u521b\u5efa <strong>LOB \u6bb5<\/strong>\uff08\u5bf9\u5e94 SEGMENT_TYPE \u4e3a LOBSEGMENT\uff09\u3001LOB \u7d22\u5f15\u6bb5\uff08LOBINDEX\uff09\uff0c\u884c\u6570\u636e\u5757\u4e2d\u4ec5\u5b58 LOB \u7684 \u201c\u6307\u9488\u201d\uff08\u5b9a\u4f4d\u5230 LOB \u6bb5\u7684\u7269\u7406\u5730\u5740\uff09\u3002<\/p>\n\n\n\n<p id=\"u3475b22b\"><strong>\u6211\u7684\u7406\u89e3\uff1a\u5927lob\u4f1a\u5b58\u50a8\u5728\u4e00\u4e2a\u5355\u72ec\u7684\u6bb5\u91cc\uff0c\u8868\u4e2d\u7684\u5927lob\u5217\u5b9e\u9645\u5b58\u50a8\u7684\u662f\u6307\u9488\uff0c\u6307\u5411\u8fd9\u4e2a\u5730\u5740<\/strong><\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"PEz4p\">2.\u6a21\u62df\u64cd\u4f5c<\/h2>\n\n\n\n<pre id=\"LfxX3\" class=\"wp-block-code\"><code>CREATE TABLE lob_test (\n  id NUMBER,\n  big_clob CLOB\n)\nLOB (big_clob) STORE AS (\n  TABLESPACE TEST_DATA\n  ENABLE STORAGE IN ROW\n);<\/code><\/pre>\n\n\n\n<pre id=\"mVh3x\" class=\"wp-block-code\"><code>-- \u67e5\u770bLOB\u6bb5\u540d\nSELECT table_name, column_name, segment_name \nFROM dba_lobs \nWHERE table_name = 'LOB_TEST' AND owner = 'TEST';\nLOB_TEST\nBIG_CLOB\nSYS_LOB0000100703C00002$$<\/code><\/pre>\n\n\n\n<pre id=\"chihc\" class=\"wp-block-code\"><code>\u63d2\u5165\u5927 LOB \u6570\u636e\uff08\u6a21\u62df \u201c\u5927 LOB \u5360\u7528\u7a7a\u95f4\u201d\uff09\n    -- \u751f\u62105000\u5b57\u8282\u7684\u968f\u673a\u6587\u672c\uff08\u8d85\u8fc7\u5185\u8054\u9608\u503c\uff09\nDECLARE\n  v_clob CLOB;\nBEGIN\n  FOR i IN 1..100 LOOP\n    v_clob := RPAD(TO_CHAR(DBMS_RANDOM.string('x', 100)), 5000, 'a');\n    INSERT INTO lob_test VALUES (i, v_clob);\n  END LOOP;\n  COMMIT;\nEND;\n\/\n\u591a\u6267\u884c\u51e0\u6b21\u6216\u5c06 100\u8c03\u4e3a\u66f4\u5927<\/code><\/pre>\n\n\n\n<p id=\"uc7851708\">\u5f53\u524d\u5360\u7528\u8868\u7a7a\u95f4\u5927\u5c0f<br>TEST_DATA LOCAL 1.00 0.00 1.00 0.30<\/p>\n\n\n\n<p id=\"ue0dfe204\">\u67e5\u8be2\u5f53\u524d LOB \u6bb5 \/ \u8868\u7a7a\u95f4\u7684\u7a7a\u95f4\u5360\u7528\uff08\u57fa\u51c6\u503c\uff09<\/p>\n\n\n\n<pre id=\"hdrfb\" class=\"wp-block-code\"><code>\nSELECT \n  segment_name,\n  tablespace_name,\n  bytes\/1024\/1024 AS used_mb -- \u5df2\u7528MB\nFROM dba_segments \nWHERE segment_name = 'SYS_LOB0000100703C00002$$' AND owner = 'TEST';<\/code><\/pre>\n\n\n\n<p id=\"u7b6a7172\">SEGMENT_NAME TABLESPACE_NAME USED_MB<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\" id=\"y4eTA\"\/>\n\n\n\n<p id=\"u9ae43184\">SYS_LOB0000100703C00002$$ TEST_DATA 18<\/p>\n\n\n\n<pre id=\"TPSNI\" class=\"wp-block-code\"><code>\u6d4b\u8bd5 DELETE \u64cd\u4f5c\nDELETE FROM lob_test;\nCOMMIT;<\/code><\/pre>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/cdn.nlark.com\/yuque\/0\/2026\/png\/59814236\/1767518491467-d66143c7-3a82-4fce-bbff-b804e0b6565b.png\" alt=\"\" title=\"\"\/><\/figure>\n\n\n\n<p id=\"ub9a2169b\">\u518d\u6b21\u67e5\u8be2\u65e0\u53d8\u5316<\/p>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/cdn.nlark.com\/yuque\/0\/2026\/png\/59814236\/1769496354936-a411c62e-4bcd-4535-b2a3-aaa96d1aa5d4.png\" alt=\"\" title=\"\"\/><\/figure>\n\n\n\n<p id=\"u8f46cd00\">\u518d\u6b21\u63d2\u5165\u6570\u636e\u5e76\u67e5\u8be2<\/p>\n\n\n\n<p id=\"u50fae7cd\">\u53c8\u63d2\u5165\u4e861400\u884c\u6570\u636e<\/p>\n\n\n\n<pre id=\"kRYXt\" class=\"wp-block-code\"><code>select count(*) from lob_test;<\/code><\/pre>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/cdn.nlark.com\/yuque\/0\/2026\/png\/59814236\/1769498677452-35174b5d-22cd-47ea-9bba-1f0c6c6ef525.png\" alt=\"\" title=\"\"\/><\/figure>\n\n\n\n<pre id=\"eY5Mg\" class=\"wp-block-code\"><code>SELECT \n  segment_name,\n  tablespace_name,\n  bytes\/1024\/1024 AS used_mb -- \u5df2\u7528MB\nFROM dba_segments \nWHERE segment_name = 'SYS_LOB0000100703C00002$$' AND owner = 'TEST';\n\nSEGMENT_NAME\t\t\t\t\t\t\t\t\t  TABLESPACE_NAME\t  USED_MB\n--------------------------------------------------------------------------------- -------------------- ----------\nSYS_LOB0000100703C00002$$\t\t\t\t\t\t\t  TEST_DATA\t\t       23<\/code><\/pre>\n\n\n\n<p id=\"u87551a1e\">\u4f7f\u7528truncate\u65b9\u5f0f\u5220\u9664<\/p>\n\n\n\n<pre id=\"iJvE5\" class=\"wp-block-code\"><code>TRUNCATE TABLE lob_test;<\/code><\/pre>\n\n\n\n<p id=\"uc04d8213\">\u5220\u9664\u540e\u518d\u6b21\u67e5\u8be2<\/p>\n\n\n\n<p id=\"u09257f72\">\u901a\u8fc7\u7ed3\u679c\u53ef\u4ee5\u770b\u5230\u5df2\u7ecf\u6210\u529f\u7684\u91ca\u653e\u4e86\u7a7a\u95f4<\/p>\n\n\n\n<pre id=\"Um16m\" class=\"wp-block-code\"><code>SQL&gt; select count(*) from lob_test;\n\n  COUNT(*)\n----------\n\t 0\n<\/code><\/pre>\n\n\n\n<pre id=\"nx2rt\" class=\"wp-block-code\"><code>SELECT \n  segment_name,\n  tablespace_name,\n  bytes\/1024\/1024 AS used_mb -- \u5df2\u7528MB\nFROM dba_segments \nWHERE segment_name = 'SYS_LOB0000100703C00002$$' AND owner = 'TEST';\n\nSEGMENT_NAME\t\t\t\t\t\t\t\t\t  TABLESPACE_NAME\t  USED_MB\n--------------------------------------------------------------------------------- -------------------- ----------\nSYS_LOB0000100703C00002$$\t\t\t\t\t\t\t  TEST_DATA\t\t    .0625\n<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"eB0q7\">3.\u4e3a\u4ec0\u4e48truncate\u53ef\u4ee5\u5220\u9664\u800cdelete\u4e0d\u884c<\/h3>\n\n\n\n<p id=\"u32e44ad2\">\u8981\u533a\u5206\u4e24\u4e2a\u547d\u4ee4\u5728<code>lob\u7a7a\u95f4<\/code>\u7ba1\u7406\u5c42\u9762\u7684<strong>\u672c\u8d28<\/strong><\/p>\n\n\n\n<p id=\"ubf451e06\"><strong>DELETE \uff1a \u4ec5\u5728 LOB \u6bb5\u5185\u7ed9\u65e7\u6570\u636e\u5757\u8d34 \u201c\u7a7a\u95f2\u6807\u7b7e\u201d\uff08\u903b\u8f91\u6807\u8bb0\uff09\uff0c\u7a7a\u95f4\u4ecd\u5c5e\u4e8e\u8be5 LOB \u6bb5\uff08\u4ec5\u53ef\u590d\u7528\uff09\uff0c\u4e0d\u5f52\u8fd8\u8868\u7a7a\u95f4 \uff0c\uff08\u4ec5\u4f5c\u903b\u8f91\u5220\u9664\uff0c\u4e0d\u505a\u7269\u7406\u5220\u9664\uff09<\/strong><\/p>\n\n\n\n<p id=\"u5064b31e\"><strong>TRUNCATE \uff1a \u76f4\u63a5\u91cd\u7f6e LOB \u6bb5\u7684\u5143\u6570\u636e\uff08HWM \u5f52 0\uff09\uff0c\u5c06 LOB \u6bb5\u7684\u6269\u5c55\u533a\uff08extent\uff09\u5168\u90e8\u5f52\u8fd8\u8868\u7a7a\u95f4\uff0c<\/strong><\/p>\n\n\n\n<p id=\"u785123d3\"><\/p>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"vjmyc\">4.\u4e3a\u4ec0\u4e48\u8981\u8fd9\u6837delete\u8981\u505a\u51fa <code>\u590d\u7528<\/code> \u7684\u8bbe\u8ba1<\/h3>\n\n\n\n<p id=\"uf22c4d1f\">Oracle \u8bbe\u8ba1 \u201c\u6bb5\u5185\u7a7a\u95f4\u590d\u7528\u201d \u7684\u6838\u5fc3\u76ee\u7684\u662f\u63d0\u5347\u6027\u80fd<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u5982\u679c\u6bcf\u6b21 DELETE \u90fd\u64e6\u9664\u6570\u636e\u5757\u3001\u91ca\u653e\u6269\u5c55\u533a\uff0c\u518d\u6bcf\u6b21 INSERT \u90fd\u91cd\u65b0\u7533\u8bf7\u6269\u5c55\u533a\uff0c\u4f1a\u4ea7\u751f\u5927\u91cf\u78c1\u76d8 I\/O \u548c\u6570\u636e\u5b57\u5178\u64cd\u4f5c\uff08\u6027\u80fd\u6781\u4f4e\uff09<\/li>\n\n\n\n<li>\u590d\u7528\u5df2\u6709\u7684\u7a7a\u95f2\u5757\uff0c\u53ea\u9700\u76f4\u63a5\u5199\u5165\u65b0\u6570\u636e\uff08\u8986\u76d6\u65e7\u5185\u5bb9\uff09\uff0c\u65e0\u9700\u7533\u8bf7\u65b0\u7a7a\u95f4<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"EXcHj\">5.\u8865\u5145<\/h3>\n\n\n\n<p id=\"uf870dd0a\">\u8fd8\u6709\u4e00\u79cd\u6e05\u7406\u65b9\u5f0f\uff1a\u5f00\u542f\u884c\u79fb\u52a8+delete+ SHRINK SPACE<\/p>\n\n\n\n<p id=\"u76309f53\">\u884c\u79fb\u52a8\u7684\u552f\u4e00\u4f5c\u7528\u662f<strong>\u5141\u8bb8 SHRINK SPACE \u8c03\u6574\u6570\u636e\u7269\u7406\u4f4d\u7f6e<\/strong>\uff0c\u4ece\u800c\u964d\u4f4e HWM\u3001\u91ca\u653e\u7a7a\u95f4\u5230\u8868\u7a7a\u95f4<\/p>\n\n\n\n<p id=\"ucf92ae8d\">\u518d\u6765\u505a\u4e00\u6b21\u64cd\u4f5c\u9a8c\u8bc1<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>\u6309\u4e4b\u524d\u7684\u65b9\u6cd5 \u63d2\u51651000\u6761\u6570\u636e<\/li>\n<\/ol>\n\n\n\n<pre id=\"vfd9i\" class=\"wp-block-code\"><code>---\u67e5\u8be2\u662f\u5426\u63d2\u5165\u6210\u529f\nselect count(*) from lob_test;\n  COUNT(*)\n----------\n      1000\n---\u67e5\u8be2\u5360\u7528\u7a7a\u95f4\nSELECT ROUND(bytes\/1024\/1024,2) AS used_mb \nFROM dba_segments \nWHERE segment_name = 'SYS_LOB0000100703C00002$$' AND owner = 'TEST';\n\n   USED_MB\n----------\n\t16\n<\/code><\/pre>\n\n\n\n<ol start=\"2\" class=\"wp-block-list\">\n<li>\u6253\u5f00\u884c\u79fb\u52a8<\/li>\n<\/ol>\n\n\n\n<pre id=\"j0sJX\" class=\"wp-block-code\"><code>ALTER TABLE lob_test ENABLE ROW MOVEMENT;<\/code><\/pre>\n\n\n\n<ol start=\"3\" class=\"wp-block-list\">\n<li>\u4f7f\u7528delete\u6e05\u7406\uff0c\u6e05\u7406\u540e\u518d\u6b21\u67e5\u8be2\u8868\u7a7a\u95f4<\/li>\n<\/ol>\n\n\n\n<pre id=\"idmLl\" class=\"wp-block-code\"><code>DELETE FROM lob_test;\nCOMMIT;\nSELECT ROUND(bytes\/1024\/1024,2) AS used_mb \nFROM dba_segments \nWHERE segment_name = 'SYS_LOB0000100703C00002$$' AND owner = 'TEST';\n   USED_MB\n----------\n\t16<\/code><\/pre>\n\n\n\n<ol start=\"4\" class=\"wp-block-list\">\n<li>\u6536\u7f29\u8868\u7a7a\u95f4<\/li>\n<\/ol>\n\n\n\n<pre id=\"dPWIg\" class=\"wp-block-code\"><code>--\u5148\u6536\u7f29\u8868\u672c\u8eab\u7684\u7a7a\u95f4\nALTER TABLE lob_test SHRINK SPACE CASCADE;\n\n--\u5355\u72ec\u6536\u7f29 LOB \u6bb5\u7684\u7a7a\u95f4\n--\u6536\u7f29 LOB \u6bb5\u5fc5\u987b\u901a\u8fc7MODIFY LOB (\u5217\u540d) (SHRINK SPACE) \u8fd9\u79cd\u72ec\u7acb\u8bed\u6cd5\n\nALTER TABLE lob_test MODIFY LOB (big_clob) (SHRINK SPACE);<\/code><\/pre>\n\n\n\n<ol start=\"5\" class=\"wp-block-list\">\n<li>\u518d\u6b21\u67e5\u8be2\u8868\u7a7a\u95f4<\/li>\n<\/ol>\n\n\n\n<p id=\"u6f0942e4\">\u53d1\u73b0\u7a7a\u95f4\u5df2\u7ecf\u6210\u529f\u6e05\u7406\uff0c\u6210\u529f\u6e05\u7406\u540e\u8bb0\u5f97<strong>\u5173\u95ed\u884c\u79fb\u52a8<\/strong><\/p>\n\n\n\n<pre id=\"ortzK\" class=\"wp-block-code\"><code> SELECT \n  segment_name,\n  tablespace_name,\n  bytes\/1024\/1024 AS used_mb -- \u5df2\u7528MB\nFROM dba_segments \nWHERE segment_name = 'SYS_LOB0000100703C00002$$' AND owner = 'TEST'; \n\nSEGMENT_NAME\t\t\t\t\t\t\t\t\t  TABLESPACE_NAME\t  USED_MB\n--------------------------------------------------------------------------------- -------------------- ----------\nSYS_LOB0000100703C00002$$\t\t\t\t\t\t\t  TEST_DATA\t\t    .0625\n<\/code><\/pre>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/cdn.nlark.com\/yuque\/0\/2026\/png\/59814236\/1769501355666-aa401249-1674-48bf-aa71-3bea25546061.png\" alt=\"\" title=\"\"\/><\/figure>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/cdn.nlark.com\/yuque\/0\/2026\/png\/59814236\/1769501895497-4316b6b1-0cf5-48e8-abfe-70a0647e0d0e.png\" alt=\"\" title=\"\"\/><\/figure>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/cdn.nlark.com\/yuque\/0\/2026\/png\/59814236\/1769501923646-46f3977f-580a-4430-b495-4b48319bbf1f.png\" alt=\"\" title=\"\"\/><\/figure>\n\n\n\n<p><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u7ed3\u8bba\uff1a\u5927lob\u53ea\u80fd\u901a\u8fc7truncate\u6216\u5f00\u542f\u884c\u79fb\u52a8\u540edelete\u7684\u65b9\u5f0f\u6e05\u7406 1.\u5148\u660e\u786e\uff1aLOB \u5b57\u6bb5\u7684\u5b58\u50a8\u672c\u8d28 [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[20],"tags":[],"class_list":["post-79","post","type-post","status-publish","format-standard","hentry","category-oracle"],"_links":{"self":[{"href":"https:\/\/yuriblog.online\/index.php\/wp-json\/wp\/v2\/posts\/79","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/yuriblog.online\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/yuriblog.online\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/yuriblog.online\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/yuriblog.online\/index.php\/wp-json\/wp\/v2\/comments?post=79"}],"version-history":[{"count":2,"href":"https:\/\/yuriblog.online\/index.php\/wp-json\/wp\/v2\/posts\/79\/revisions"}],"predecessor-version":[{"id":81,"href":"https:\/\/yuriblog.online\/index.php\/wp-json\/wp\/v2\/posts\/79\/revisions\/81"}],"wp:attachment":[{"href":"https:\/\/yuriblog.online\/index.php\/wp-json\/wp\/v2\/media?parent=79"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/yuriblog.online\/index.php\/wp-json\/wp\/v2\/categories?post=79"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/yuriblog.online\/index.php\/wp-json\/wp\/v2\/tags?post=79"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}