A few minor Unicode collation customization improvements were made,

which makes it possible to add more world language collations
with very complex collation rules (e.g. Myanmar):
- Weight string for a single character in a user defined collation
  was erroneously limited to 7 weights (instead of 8 weights).
  Added an extra element in the user-defined weight arrays,
  to fit 8 non-zero weights.
- Weight string limit for contractions was made two times longer (16 weights),
  which allows longer contractions without affecting the performance
  of filesort.
- A user-defined collation now refuses to initialize and reports an error
  in case if a weight string gets longer than 8 weights for a single character,
  or longer than 16 weights for a contraction. Previously weight strings
  for such characters (and contractions) were cut, so a collation
  could silently start with wrong rules.
- Fixed a bug in handling rules like "&a << b" in combination with
  shift-after-method="expand". The primary weight for "b" was not
  correctly calculated, which erroneously made "b" primary greater than "a"
  instead of primary equal to "a".

1 files changed, 14 insertions, 2 deletions

diff --git a/include/m_ctype.h b/include/m_ctype.h
index b9682df12bf..1b60f2091b1 100644
--- a/include/m_ctype.h
+++ b/include/m_ctype.h
@@ -88,13 +88,25 @@ extern MY_UNICASE_INFO my_unicase_mysql500;
 extern MY_UNICASE_INFO my_unicase_unicode520;
 
 #define MY_UCA_MAX_CONTRACTION 6
-#define MY_UCA_MAX_WEIGHT_SIZE 8
+/*
+  The DUCET tables in ctype-uca.c are dumped with a limit of 8 weights
+  per character. cs->strxfrm_multiply is set to 8 for all UCA based collations.
+
+  In language-specific UCA collations (with tailorings) we also do not allow
+  a single character to have more than 8 weights to stay with the same
+  strxfrm_multiply limit. Note, contractions are allowed to have twice longer
+  weight strings (up to 16 weights). As a contraction consists of at
+  least 2 characters, this makes sure that strxfrm_multiply ratio of 8
+  is respected.
+*/
+#define MY_UCA_MAX_WEIGHT_SIZE (8+1)               /* Including 0 terminator */
+#define MY_UCA_CONTRACTION_MAX_WEIGHT_SIZE (2*8+1) /* Including 0 terminator */
 #define MY_UCA_WEIGHT_LEVELS   1
 
 typedef struct my_contraction_t
 {
   my_wc_t ch[MY_UCA_MAX_CONTRACTION];   /* Character sequence              */
-  uint16 weight[MY_UCA_MAX_WEIGHT_SIZE];/* Its weight string, 0-terminated */
+  uint16 weight[MY_UCA_CONTRACTION_MAX_WEIGHT_SIZE];/* Its weight string, 0-terminated */
   my_bool with_context;
 } MY_CONTRACTION;