forked from docs/doc-exports
Lu, Huayi
e6fa411af0
Reviewed-by: Pruthi, Vineet <vineet.pruthi@t-systems.com> Co-authored-by: Lu, Huayi <luhuayi@huawei.com> Co-committed-by: Lu, Huayi <luhuayi@huawei.com>
76 lines
18 KiB
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76 lines
18 KiB
HTML
<a name="EN-US_TOPIC_0000001188323584"></a><a name="EN-US_TOPIC_0000001188323584"></a>
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<h1 class="topictitle1">Compatibility with Earlier Versions</h1>
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<div id="body8662426"><p id="EN-US_TOPIC_0000001188323584__en-us_topic_0059778091_p16492056189">This section describes the parameter control of the downward compatibility and external compatibility features of <span id="EN-US_TOPIC_0000001188323584__text1356675028">GaussDB(DWS)</span>. Backward compatibility of the database system provides support for the application of databases of earlier versions. This section describes parameters used for controlling backward compatibility of a database.</p>
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<div class="section" id="EN-US_TOPIC_0000001188323584__se7cd4bba8e964f99b2bc906f9642d08b"><h4 class="sectiontitle">array_nulls</h4><p id="EN-US_TOPIC_0000001188323584__a9376210b7e844c3881725f7d524e2155"><strong id="EN-US_TOPIC_0000001188323584__en-us_topic_0059778091_en-us_topic_0058967545_b67083165">Parameter description</strong>: Determines whether the array input parser recognizes unquoted NULL as a null array element.</p>
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<p id="EN-US_TOPIC_0000001188323584__a08d782463f144356b25d6f937a41fd8a"><strong id="EN-US_TOPIC_0000001188323584__b07910253270">Type</strong>: USERSET</p>
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<p id="EN-US_TOPIC_0000001188323584__a1c2ed5c64d2548c0b2db9b3f4ed65b46"><strong id="EN-US_TOPIC_0000001188323584__en-us_topic_0059778091_en-us_topic_0058967545_b10343138">Value range</strong>: Boolean</p>
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<ul id="EN-US_TOPIC_0000001188323584__u41b2a3e7c3ab4ab997a7fc5245eeaa03"><li id="EN-US_TOPIC_0000001188323584__l90276678816b4fdc92755d50e62d07f1"><strong>on</strong> indicates that null values can be entered in arrays.</li><li id="EN-US_TOPIC_0000001188323584__le99471b4e09946bca11e3070a92c85fc"><strong>off</strong> indicates backward compatibility with the old behavior. Arrays containing <strong id="EN-US_TOPIC_0000001188323584__b1757471543">NULL</strong> values can still be created when this parameter is set to <strong id="EN-US_TOPIC_0000001188323584__b149829551335">off</strong>.</li></ul>
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<p id="EN-US_TOPIC_0000001188323584__ab6f025b0908f46cba96a59e07acfa18c"><strong id="EN-US_TOPIC_0000001188323584__en-us_topic_0059778346_a30e99140fb09438ab2bb77f75bd21bb4">Default value</strong>: <strong id="EN-US_TOPIC_0000001188323584__en-us_topic_0059778346_en-us_topic_0058967649_b842352706195040">on</strong></p>
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</div>
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<div class="section" id="EN-US_TOPIC_0000001188323584__se986137836604057aa256aa57b8b2a15"><h4 class="sectiontitle">backslash_quote</h4><p id="EN-US_TOPIC_0000001188323584__a8885c17e58c546d6bf3594ff4bbbb798"><strong id="EN-US_TOPIC_0000001188323584__en-us_topic_0059778091_en-us_topic_0058967545_b47202394">Parameter description</strong>: Determines whether a single quotation mark can be represented by \' in a string text.</p>
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<p id="EN-US_TOPIC_0000001188323584__p32565815920"><strong id="EN-US_TOPIC_0000001188323584__b133491526152711">Type</strong>: USERSET</p>
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<div class="notice" id="EN-US_TOPIC_0000001188323584__neca5b125d9d54c6688a13199023c9a4b"><span class="noticetitle"><img src="public_sys-resources/notice_3.0-en-us.png"> </span><div class="noticebody"><p id="EN-US_TOPIC_0000001188323584__a21c7b8bb43684ab785f5a75a1b1cbc9b">When the string text meets the SQL standards, \ has no other meanings. This parameter only affects the handling of non-standard-conforming string texts, including escape string syntax (E'...').</p>
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</div></div>
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<p id="EN-US_TOPIC_0000001188323584__ad0fefc2ac80e4542873d3eaa9d3ad00d"><strong id="EN-US_TOPIC_0000001188323584__en-us_topic_0059778091_en-us_topic_0058967545_b41199681">Value range</strong>: enumerated values</p>
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<ul id="EN-US_TOPIC_0000001188323584__u083f8fde767d4cc08b473e7559d883c3"><li id="EN-US_TOPIC_0000001188323584__l5301eb7d1f684e0fa57c0051841cccb8"><strong>on</strong> indicates that the use of \' is always allowed.</li><li id="EN-US_TOPIC_0000001188323584__l113e3273cfac42edb8c0df9111e99efa"><strong>off</strong> indicates that the use of \' is rejected.</li><li id="EN-US_TOPIC_0000001188323584__la420e534c8df4343bf1a99a0864ba930"><strong>safe_encoding</strong> indicates that the use of \' is allowed only when client encoding does not allow ASCII \ within a multibyte character.</li></ul>
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<p id="EN-US_TOPIC_0000001188323584__a0fb40d89b4da4d51a4d5c1d0b38cdbc6"><strong id="EN-US_TOPIC_0000001188323584__b1892783145551">Default value</strong>: <strong id="EN-US_TOPIC_0000001188323584__b842352706135740">safe_encoding</strong></p>
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</div>
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<div class="section" id="EN-US_TOPIC_0000001188323584__sf96b76948b0447b9b155f1bafb728524"><h4 class="sectiontitle">default_with_oids</h4><p id="EN-US_TOPIC_0000001188323584__ae9c85812b3f2450fa6e688d49703fbda"><strong>Parameter description</strong>: Determines whether <strong>CREATE TABLE</strong> and <strong>CREATE TABLE AS</strong> include an <strong>OID</strong> field in newly-created tables if neither <strong>WITH OIDS</strong> nor <strong>WITHOUT OIDS</strong> is specified. It also determines whether OIDs will be included in tables created by <strong id="EN-US_TOPIC_0000001188323584__b84235270616217">SELECT INTO</strong>.</p>
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<p id="EN-US_TOPIC_0000001188323584__a40a475f41f394b5688db420676633625">It is not recommended that OIDs be used in user tables. Therefore, this parameter is set to <strong>off</strong> by default. When OIDs are required for a particular table, <strong id="EN-US_TOPIC_0000001188323584__b84235270616229">WITH OIDS</strong> needs to be specified during the table creation.</p>
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<p id="EN-US_TOPIC_0000001188323584__p64676831019"><strong id="EN-US_TOPIC_0000001188323584__b15709102613277">Type</strong>: USERSET</p>
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<p id="EN-US_TOPIC_0000001188323584__a37f5a843f0544b92bfbad8a60a3a7464"><strong id="EN-US_TOPIC_0000001188323584__en-us_topic_0059778091_a24cd3a355dfe409d98fe47d3b5b09935">Value range</strong>: Boolean</p>
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<ul id="EN-US_TOPIC_0000001188323584__u5532ae5896f941c585ba4466d1821db5"><li id="EN-US_TOPIC_0000001188323584__l2606d23dafb046d0ae727e242906172e"><strong id="EN-US_TOPIC_0000001188323584__b842352706173352">on</strong> indicates <strong id="EN-US_TOPIC_0000001188323584__b8423527061782">CREATE TABLE</strong> and <strong id="EN-US_TOPIC_0000001188323584__b8423527061788">CREATE TABLE AS</strong> can include an <strong id="EN-US_TOPIC_0000001188323584__b84235270617816">OID</strong> field in newly-created tables.</li><li id="EN-US_TOPIC_0000001188323584__l51f2573df39a4bd38e99c9028c145281"><strong id="EN-US_TOPIC_0000001188323584__b197281440173519">off</strong> indicates <strong id="EN-US_TOPIC_0000001188323584__b84235270617826">CREATE TABLE</strong> and <strong id="EN-US_TOPIC_0000001188323584__b84235270617833">CREATE TABLE AS</strong> cannot include any <strong id="EN-US_TOPIC_0000001188323584__b84235270617837">OID</strong> field in newly-created tables.</li></ul>
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<p id="EN-US_TOPIC_0000001188323584__a4a745e3ea2524e0a9ec6cef844927b3b"><strong id="EN-US_TOPIC_0000001188323584__b55233292105553">Default value</strong>: <strong id="EN-US_TOPIC_0000001188323584__b842352706172155">off</strong></p>
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</div>
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<div class="section" id="EN-US_TOPIC_0000001188323584__sec7a220353a241138f4b93579ed99826"><h4 class="sectiontitle">escape_string_warning</h4><p id="EN-US_TOPIC_0000001188323584__a94517f4903d1490baf2ac14be013f46c"><strong id="EN-US_TOPIC_0000001188323584__en-us_topic_0059778091_en-us_topic_0058967545_b30049279">Parameter description</strong>: Specifies a warning on directly using a backslash (\) as an escape in an ordinary character string.</p>
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<ul id="EN-US_TOPIC_0000001188323584__u45326a63b469440aac2ab3e04dab17de"><li id="EN-US_TOPIC_0000001188323584__l23578b5aa28b4039bd784a2d2d4904c7">Applications that wish to use a backslash (\) as an escape need to be modified to use escape string syntax (E'...'). This is because the default behavior of ordinary character strings is now to treat the backslash as an ordinary character in each SQL standard.</li><li id="EN-US_TOPIC_0000001188323584__l571e8e5d62d04b0488adf3625b1e253b">This variable can be enabled to help locate codes that need to be changed.</li></ul>
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<p id="EN-US_TOPIC_0000001188323584__p849922031020"><strong id="EN-US_TOPIC_0000001188323584__b4947726112719">Type</strong>: USERSET</p>
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<p id="EN-US_TOPIC_0000001188323584__ae58bc1122dab464a8e95eca9d61063a7"><strong id="EN-US_TOPIC_0000001188323584__en-us_topic_0059778091_en-us_topic_0058967545_b25464918">Value range</strong>: Boolean</p>
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<p id="EN-US_TOPIC_0000001188323584__aac4809b03a0b4e43b292d67f5f2708a9"><strong id="EN-US_TOPIC_0000001188323584__b185204704">Default value</strong>: <strong id="EN-US_TOPIC_0000001188323584__b1035551243">on</strong></p>
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</div>
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<div class="section" id="EN-US_TOPIC_0000001188323584__s6b76d9c90df44be7aaac92e9a8a33316"><h4 class="sectiontitle">lo_compat_privileges</h4><p id="EN-US_TOPIC_0000001188323584__af7160d6a03d54ca495d7163d229bf8ac"><strong id="EN-US_TOPIC_0000001188323584__en-us_topic_0059778091_en-us_topic_0058967545_b8825287">Parameter description</strong>: Determines whether to enable backward compatibility for the privilege check of large objects.</p>
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<p id="EN-US_TOPIC_0000001188323584__p0493616127"><strong id="EN-US_TOPIC_0000001188323584__b1964214279275">Type</strong>: SUSET</p>
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<p id="EN-US_TOPIC_0000001188323584__a2dea28d77f92444e9f850bc843134074"><strong id="EN-US_TOPIC_0000001188323584__en-us_topic_0059778091_en-us_topic_0058967545_b54002014">Value range</strong>: Boolean</p>
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<p id="EN-US_TOPIC_0000001188323584__a273225a0b2674321aeb7e315d40c5464"><strong>on</strong> indicates that the privilege check is disabled when users read or modify large objects. This setting is compatible with versions earlier than PostgreSQL 9.0.</p>
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<p id="EN-US_TOPIC_0000001188323584__ab5dfbd4f056a4b44899a82ff3b509e17"><strong id="EN-US_TOPIC_0000001188323584__b676248790">Default value</strong>: <strong id="EN-US_TOPIC_0000001188323584__b476242123">off</strong></p>
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</div>
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<div class="section" id="EN-US_TOPIC_0000001188323584__s9654bf1fd76f477ea2cc1f2c7b490ca0"><h4 class="sectiontitle">quote_all_identifiers</h4><p id="EN-US_TOPIC_0000001188323584__ae3cb992f01754d95b8a23da3bb58f8c6"><strong id="EN-US_TOPIC_0000001188323584__en-us_topic_0059778091_en-us_topic_0058967545_b61943053">Parameter description</strong>: When the database generates SQL, this parameter forcibly quotes all identifiers even if they are not keywords. This will affect the output of EXPLAIN as well as the results of functions, such as pg_get_viewdef. For details, see the <strong id="EN-US_TOPIC_0000001188323584__b84235270615359">--quote-all-identifiers</strong> parameter of <strong id="EN-US_TOPIC_0000001188323584__b84235270615410">gs_dump</strong>.</p>
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<p id="EN-US_TOPIC_0000001188323584__p185092395107"><strong id="EN-US_TOPIC_0000001188323584__b7150230142715">Type</strong>: USERSET</p>
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<p id="EN-US_TOPIC_0000001188323584__a419b6bcddde24a29a3cd0d339a32cbc4"><strong id="EN-US_TOPIC_0000001188323584__en-us_topic_0059778091_en-us_topic_0058967545_b47987075">Value range</strong>: Boolean</p>
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<ul id="EN-US_TOPIC_0000001188323584__u1cb416d1467848e8b0f63b6456498002"><li id="EN-US_TOPIC_0000001188323584__lebe572b3a1614a14bfb29f7d1f79c865"><strong id="EN-US_TOPIC_0000001188323584__b842352706172849">on</strong> indicates the forcible quotation function is enabled.</li><li id="EN-US_TOPIC_0000001188323584__lc675f7d307b2417cac9d972743c5deff"><strong id="EN-US_TOPIC_0000001188323584__b955432461172922">off</strong> indicates the forcible quotation function is disabled.</li></ul>
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<p id="EN-US_TOPIC_0000001188323584__ad312273bd52f49c6875c52f7ad99fe17"><strong id="EN-US_TOPIC_0000001188323584__b1461983302">Default value</strong>: <strong id="EN-US_TOPIC_0000001188323584__b507355291">off</strong></p>
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</div>
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<div class="section" id="EN-US_TOPIC_0000001188323584__s128b88b800ed4fa084a6526d86e6ec95"><h4 class="sectiontitle">sql_inheritance</h4><p id="EN-US_TOPIC_0000001188323584__aa57d801ca4934909b2ef9de06a0cff13"><strong id="EN-US_TOPIC_0000001188323584__en-us_topic_0059778091_en-us_topic_0058967545_b30908672">Parameter description</strong>: Determines whether to inherit semantics.</p>
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<p id="EN-US_TOPIC_0000001188323584__p91499081115"><strong id="EN-US_TOPIC_0000001188323584__b146871130112710">Type</strong>: USERSET</p>
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<p id="EN-US_TOPIC_0000001188323584__a0d33dcc9b38947139053235a35935a82"><strong id="EN-US_TOPIC_0000001188323584__en-us_topic_0059778091_en-us_topic_0058967545_b33446144">Value range</strong>: Boolean</p>
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<p id="EN-US_TOPIC_0000001188323584__ab71739e701534782b2aeea3269a0d201"><strong>off</strong> indicates that child tables cannot be accessed by various commands. That is, an ONLY keyword is used by default. This setting is compatible with versions earlier than PostgreSQL 7.1.</p>
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<p id="EN-US_TOPIC_0000001188323584__a050ef5e10863448e87a4a825be18a6b7"><strong id="EN-US_TOPIC_0000001188323584__b1419927358">Default value</strong>: <strong id="EN-US_TOPIC_0000001188323584__b1163160967">on</strong></p>
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</div>
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<div class="section" id="EN-US_TOPIC_0000001188323584__se5a29ca94bc34ee8a3e0894d5b94ebf6"><h4 class="sectiontitle">standard_conforming_strings</h4><p id="EN-US_TOPIC_0000001188323584__a36b415b38a8246529cb2fdf164a965a6"><strong id="EN-US_TOPIC_0000001188323584__en-us_topic_0059778091_en-us_topic_0058967545_b10677501">Parameter description</strong>: Determines whether ordinary string texts ('...') treat backslashes as ordinary texts as specified in the SQL standard.</p>
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<ul id="EN-US_TOPIC_0000001188323584__u941327608216456794e918fe80b97212"><li id="EN-US_TOPIC_0000001188323584__l2c7284e598074d5f97b9ac6533cfbb79">Applications can check this parameter to determine how string texts will be processed.</li><li id="EN-US_TOPIC_0000001188323584__l32f5df4c036b48d8952114da5fddb0bf">It is recommended that characters be escaped by using the escape string syntax (E'...').</li></ul>
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<p id="EN-US_TOPIC_0000001188323584__p086142815116"><strong id="EN-US_TOPIC_0000001188323584__b486263017277">Type</strong>: USERSET</p>
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<p id="EN-US_TOPIC_0000001188323584__a57df995f03ef4bc388adf6086f87c4a4"><strong id="EN-US_TOPIC_0000001188323584__en-us_topic_0059778091_en-us_topic_0058967545_b29758026">Value range</strong>: Boolean</p>
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<ul id="EN-US_TOPIC_0000001188323584__ubeb3fb29b1ce472b90860ae3c6139566"><li id="EN-US_TOPIC_0000001188323584__l7ca7c4e873df446eba90f18e7257e77b"><strong id="EN-US_TOPIC_0000001188323584__b84235270610156">on</strong> indicates that the function is enabled.</li><li id="EN-US_TOPIC_0000001188323584__l250ab304423b4d13b9b343784f511161"><strong>off</strong> indicates that the function is disabled.</li></ul>
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<p id="EN-US_TOPIC_0000001188323584__a581b403da2fb479d9e3b190383429174"><strong id="EN-US_TOPIC_0000001188323584__b628501942">Default value</strong>: <strong id="EN-US_TOPIC_0000001188323584__b1151345454">on</strong></p>
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</div>
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<div class="section" id="EN-US_TOPIC_0000001188323584__s26e681b01a5642c994fedcbec98e6141"><h4 class="sectiontitle">synchronize_seqscans</h4><p id="EN-US_TOPIC_0000001188323584__abd0eb6a9630b45228f3439ed340dc370"><strong id="EN-US_TOPIC_0000001188323584__en-us_topic_0059778091_en-us_topic_0058967545_b49825593">Parameter description</strong>: Controls sequential scans of tables to synchronize with each other. Concurrent scans read the same data block about at the same time and share the I/O workload.</p>
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<p id="EN-US_TOPIC_0000001188323584__p14148193811114"><strong id="EN-US_TOPIC_0000001188323584__b1277331122716">Type</strong>: USERSET</p>
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<p id="EN-US_TOPIC_0000001188323584__aba8e9fc1fb5046448b3b0f5f30aa2821"><strong id="EN-US_TOPIC_0000001188323584__en-us_topic_0059778091_en-us_topic_0058967545_b56206746">Value range</strong>: Boolean</p>
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<ul id="EN-US_TOPIC_0000001188323584__u11a4efb375c34810ade490d372195c8e"><li id="EN-US_TOPIC_0000001188323584__l47aafedca2f14e7eb5ac2fefac253840"><strong>on</strong> indicates that a scan may start in the middle of the table and then "wrap around" the end to cover all rows to synchronize with the activity of scans already in progress. This may result in unpredictable changes in the row ordering returned by queries that have no ORDER BY clause.</li><li id="EN-US_TOPIC_0000001188323584__l7682bfab4b9546008d940f974adcccd6"><strong id="EN-US_TOPIC_0000001188323584__b842352706173146">off</strong> indicates that the scan always starts from the table heading.</li></ul>
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<p id="EN-US_TOPIC_0000001188323584__a906e07eea8ba4993afef4565fb050a64"><strong id="EN-US_TOPIC_0000001188323584__b277610655111">Default value</strong>: <strong id="EN-US_TOPIC_0000001188323584__b12777663517">on</strong></p>
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</div>
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<div class="section" id="EN-US_TOPIC_0000001188323584__section11856720221716"><h4 class="sectiontitle">enable_beta_features</h4><p id="EN-US_TOPIC_0000001188323584__p20870245221716"><strong id="EN-US_TOPIC_0000001188323584__b1681451134413">Parameter description</strong>: Controls whether certain limited features, such as GDS table join, are available. These features are not explicitly prohibited in earlier versions, but are not recommended due to their limitations in certain scenarios.</p>
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<p id="EN-US_TOPIC_0000001188323584__p492024913111"><strong id="EN-US_TOPIC_0000001188323584__b122631931162716">Type</strong>: USERSET</p>
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<p id="EN-US_TOPIC_0000001188323584__p27599305221716"><strong id="EN-US_TOPIC_0000001188323584__b116441933134520">Value range</strong>: Boolean</p>
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<ul id="EN-US_TOPIC_0000001188323584__ul20951272221716"><li id="EN-US_TOPIC_0000001188323584__li54343728221716"><strong id="EN-US_TOPIC_0000001188323584__b18119163424512">on</strong> indicates that the features are enabled and forward compatible, but may incur errors in certain scenarios.</li><li id="EN-US_TOPIC_0000001188323584__li50073814221825"><strong id="EN-US_TOPIC_0000001188323584__b1174374314512">off</strong> indicates that the features are disabled.</li></ul>
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<p id="EN-US_TOPIC_0000001188323584__p39765810221716"><strong id="EN-US_TOPIC_0000001188323584__b79781096516">Default value</strong>: <strong id="EN-US_TOPIC_0000001188323584__b997913985111">off</strong></p>
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</div>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="dws_04_0929.html">Version and Platform Compatibility</a></div>
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</div>
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</div>
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