ORCA: order-preserving LINT mapping for string statistics#1742
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Replace the hash-based LINT mapping used by ORCA's varchar/text/bpchar statistics with an order-preserving 7-byte locale sort-key prefix, so that single-column MCV and histogram estimates respect the column's collation order instead of collapsing to hash values.
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Previously, string statistics were mapped to LINT values via hashtext, which does not preserve lexicographic order. As a result, ORCA's range/comparison estimates on string columns could be wildly inaccurate. This change introduces an order-preserving mapping so that a < b on strings implies LINT(a) < LINT(b), restoring meaningful selectivity estimates for inequality predicates on text columns.
Replace the hash-based LINT mapping used by ORCA's varchar/text/bpchar statistics with an order-preserving 7-byte locale sort-key prefix, so that single-column MCV and histogram estimates respect the column's collation order instead of collapsing to hash values.
Fixes #ISSUE_Number
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make installcheckmake -C src/test installcheck-cbdb-parallelImpact
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