THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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Lateral view is used in conjunction with user-defined table generating functions such as explode(). As mentioned in Built-in Table-Generating Functions, a UDTF generates one or more output rows for each input row. A lateral view first applies the UDTF to each row of base table and then joins resulting output rows to the input rows to form a virtual table having the supplied table alias.
Important note
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| Info | ||
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Prior to Hive 0.6.0, lateral view |
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did not support the predicate push-down optimization |
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. In Hive 0.5.0 and earlier, if you used a WHERE clause |
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your query may not |
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have compiled. A workaround was to add |
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: Predicate push down does not work with UDTF's. |
Example
Consider the following base table named pageAds. It has two columns: pageid (name of the page) and adid_list (an array of ads appearing on the page):
string pageid | Array<int> adid_list | ||
<ac:structured-macro ac:name="unmigrated-wiki-markup" ac:schema-version="1" ac:macro-id="475f8c7f084ddb02-b376caca-48fe4f40-918cb3bd-7fb971b8cd942f981ac5493b"><ac:plain-text-body><![CDATA[ | "front_page" | [1, 2, 3] | ]]></ac:plain-text-body></ac:structured-macro> |
<ac:structured-macro ac:name="unmigrated-wiki-markup" ac:schema-version="1" ac:macro-id="5a8c8bed1943d05a-70ae79df-447b425c-9825a394-dbb9a6879c08639094391a7e"><ac:plain-text-body><![CDATA[ | "contact_page" | [3, 4, 5] | ]]></ac:plain-text-body></ac:structured-macro> |
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Array<int> col1 | Array<string> col2 | ||
<ac:structured-macro ac:name="unmigrated-wiki-markup" ac:schema-version="1" ac:macro-id="2b062d5ee58fae9b-f21e3930-42214bac-b0bfb09c-c1e99410a677c337ca70436f"><ac:plain-text-body><![CDATA[ | [1, 2] | [a", "b", "c"] | ]]></ac:plain-text-body></ac:structured-macro> |
<ac:structured-macro ac:name="unmigrated-wiki-markup" ac:schema-version="1" ac:macro-id="d03d57e49072d5b6-29015321-48794234-8c07bcc5-42fc6ad213be75c1c96c6885"><ac:plain-text-body><![CDATA[ | [3, 4] | [d", "e", "f"] | ]]></ac:plain-text-body></ac:structured-macro> |
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int mycol1 | Array<string> col2 | ||
<ac:structured-macro ac:name="unmigrated-wiki-markup" ac:schema-version="1" ac:macro-id="a62c84e163cee291-a9b9527f-4fb045ad-9aeb9c31-493c1cf60f0545f3896db00c"><ac:plain-text-body><![CDATA[ | 1 | [a", "b", "c"] | ]]></ac:plain-text-body></ac:structured-macro> |
<ac:structured-macro ac:name="unmigrated-wiki-markup" ac:schema-version="1" ac:macro-id="b9028b369f94223e-cc81929e-45074f84-b44cbc86-b3a900d37bb09668d59e6b83"><ac:plain-text-body><![CDATA[ | 2 | [a", "b", "c"] | ]]></ac:plain-text-body></ac:structured-macro> |
<ac:structured-macro ac:name="unmigrated-wiki-markup" ac:schema-version="1" ac:macro-id="60777a791214e1db-30d3f27e-45544d9c-94549c67-afc327067faa269cc410376b"><ac:plain-text-body><![CDATA[ | 3 | [d", "e", "f"] | ]]></ac:plain-text-body></ac:structured-macro> |
<ac:structured-macro ac:name="unmigrated-wiki-markup" ac:schema-version="1" ac:macro-id="19d734af9c70dea1-62397131-44ec413c-a604b14b-6ac2bfe492a48bbc5727901b"><ac:plain-text-body><![CDATA[ | 4 | [d", "e", "f"] | ]]></ac:plain-text-body></ac:structured-macro> |
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