If you’re getting an error that reads “source array too small” when updating an array in PostgreSQL, it’s probably because you’re passing a slice that’s smaller than your specified range. For example, if you specify a range that covers four elements but provide an array that contains just three elements, then you’d get this error.<\/p>\n\n\n\n
To fix the error, be sure to provide an an array that contains at least as many elements as are specified in the range. <\/p>\n\n\n\n\n\n\n\n
Suppose we have the following array:<\/p>\n\n\n\n
SELECT c2 FROM t1 WHERE c1 = 1;<\/code><\/pre>\n\n\n\nResult:<\/p>\n\n\n\n
{0,7,6,9,8,12,14}<\/pre>\n\n\n\nAnd suppose we try to update it like this:<\/p>\n\n\n\n
UPDATE t1 \nSET c2[1:3] = '{1,2}'\nWHERE c1 = 1;<\/code><\/pre>\n\n\n\nResult:<\/p>\n\n\n\n
ERROR: source array too small<\/pre>\n\n\n\nI got the error because my range specifies three elements but my array only contains two elements.<\/p>\n\n\n\n
Solution<\/h2>\n\n\n\n
We can fix this issue either by reducing the range to match the array:<\/p>\n\n\n\n
UPDATE t1 \nSET c2[1:2] = '{1,2}'\nWHERE c1 = 1;\n\nSELECT c2 FROM t1 WHERE c1 = 1;<\/code><\/pre>\n\n\n\nResult:<\/p>\n\n\n\n
{1,2,6,9,8,12,14}<\/pre>\n\n\n\nOr we can increase the number of elements in the array to match the range:<\/p>\n\n\n\n
UPDATE t1 \nSET c2[1:3] = '{1,2,3}'\nWHERE c1 = 1;\n\nSELECT c2 FROM t1 WHERE c1 = 1;<\/code><\/pre>\n\n\n\nResult:<\/p>\n\n\n\n
{1,2,3,9,8,12,14}<\/pre>\n\n\n\nNormally we would want the number of elements to match the range exactly, but it is possible to provide a larger slice. When we do this, the specified range takes precedence. Therefore, it will take as many elements from the new array as are specified in the range.<\/p>\n\n\n\n
Here’s an example of what I mean:<\/p>\n\n\n\n
UPDATE t1 \nSET c2[1:2] = '{5,6,7}'\nWHERE c1 = 1;\n\nSELECT c2 FROM t1 WHERE c1 = 1;<\/code><\/pre>\n\n\n\nResult:<\/p>\n\n\n\n
{5,6,3,9,8,12,14}<\/pre>\n\n\n\nIn this case only the first two elements were updated, even though I provided an array with three elements. That’s because the range was only two.<\/p>\n","protected":false},"excerpt":{"rendered":"
If you’re getting an error that reads “source array too small” when updating an array in PostgreSQL, it’s probably because you’re passing a slice that’s smaller than your specified range. For example, if you specify a range that covers four elements but provide an array that contains just three elements, then you’d get this error. … Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[40],"tags":[169,76,10],"class_list":["post-36089","post","type-post","status-publish","format-standard","hentry","category-postgresql","tag-arrays","tag-errors","tag-how-to"],"_links":{"self":[{"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/posts\/36089","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/comments?post=36089"}],"version-history":[{"count":4,"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/posts\/36089\/revisions"}],"predecessor-version":[{"id":36102,"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/posts\/36089\/revisions\/36102"}],"wp:attachment":[{"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/media?parent=36089"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/categories?post=36089"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/tags?post=36089"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}