Details
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Bug
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Status: Closed
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Major
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Resolution: Fixed
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None
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None
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None
Description
While fixing (#168 | FLINK-168)/([#169|https://github.com/JulianHyde/optiq/issues/169] | FLINK-169) I realized `optiq` does not support case-insensitive table names for `Casing.UNCHANGED`.
Here is the failing case (it does not yet exists in `optiq` test suite):
```java
/** Tests using case-insensitive matching of table names */
@Test public void testCaseInsensitiveTables() {
final SqlTester tester1 = tester
.withLex(ConnectionConfig.Lex.SQL_SERVER);
tester1.checkQuery("select eMp.* from (select * from emp as EmP)");
}
```
```
Validator threw unexpected exception; query [select eMp.* from (select * from emp as EmP)]; exception [Unknown identifier 'eMp']; pos [line 1 col 8 thru line 1 col 8]
```
I guess the cause is `OptiqCatalogReader` that tries to use `map.get`: `schema.compositeTableMap.get(name)`
I see several possible solutions, however I do not have performance tests, thus I am not sure how to measure the impact.
1) Add one more map that maps `name.toUpper() -> Table`. The problem is `equalsIgnoreCase` is not the same as comparing two strings converted to upper (or lower) case.
See relevant comment in `String#equalsIgnoreCase`:
```
// If characters don't match but case may be ignored,
// try converting both characters to uppercase.
// If the results match, then the comparison scan should
// continue.
char u1 = Character.toUpperCase(c1);
char u2 = Character.toUpperCase(c2);
if (u1 == u2) {
continue;
}
// Unfortunately, conversion to uppercase does not work properly
// for the Georgian alphabet, which has strange rules about case
// conversion. So we need to make one last check before
// exiting.
if (Character.toLowerCase(u1) == Character.toLowerCase(u2)) {
continue;
}
```
2) Use `TreeMap` + `java.text.CollationKey`. This will provide locale-dependent case-insensitive map, however the performance will degrade 
3) Use both approaches: use special `HashMap` of previously resolved tables. When no table is found there, look into `TreeMap` as a source-of-case-insensitive-truth.
The same might be relevant for wide types (e.g. types with 1000 columns)
---------------- Imported from GitHub ----------------
Url: https://github.com/julianhyde/optiq/issues/173
Created by: vlsi
Labels:
Created at: Sat Mar 08 19:29:38 CET 2014
State: closed