Update doc/shared_schema.md to describe the shell tool ".shared-schema" dot-command.

FossilOrigin-Name: 0ce2092a5968d75d014fdc238391c362a9600c28bf18cdc631e98259a5278712

diff --git a/doc/shared_schema.md b/doc/shared_schema.md
index 38c325289aebdb9bbee5e2a75006df6f6841049a..a8a7d32a35273f1899f7ff32b658bd7ef2ae2957 100644 (file)
--- a/doc/shared_schema.md
+++ b/doc/shared_schema.md
@@ -31,6 +31,65 @@ SQLITE_DBSTATUS_SCHEMA_USED sqlite3_db_status() verb
 distributes the memory used for a shared schema object evenly between all
 database connections that share it.
 
+## The ".shared-schema" Command
+
+The shell tool on this branch contains a special dot-command to help with
+managing databases. The ".shared-schema" dot-command can be used to test
+whether or not two databases are similar enough to share in-memory schemas,
+and to fix minor problems that prevent them from doing so. To test if
+two or more database are compatible, one database is opened directly using 
+the shell tool and the following command issued:
+
+        .shared-schema check <database-1> [<database-2>]...
+
+where &lt;database-1;&gt; etc. are replaced with the names of database files
+on disk. For each database specified on the command line, a single line of
+output is produced. If the database can share an in-memory schema with the
+main database opened by the shell tool, the output is of the form:
+
+        <database> is compatible
+
+Otherwise, if the database cannot share a schema with the main db, the output
+is of the form:
+
+        <database> is NOT compatible (<reason>)
+
+where &lt;reason&gt; indicates the cause of the incompatibility. &lt;reason&gt;
+is always one of the following.
+
+<ul>
+  <li> <b>objects</b> - the databases contain a different set schema objects
+  (tables, indexes, views and triggers).
+
+  <li> <b>SQL</b> - the databases contain the same set of objects, but the SQL
+  statements used to create them were not the same.
+
+  <li> <b>root pages</b> - the databases contain the same set of objects created
+  by the same SQL statements, but the root pages are not the same.
+
+  <li> <b>order of sqlite&#95;master rows</b> - the databases contain the same
+  set of objects created by the same SQL statements with the same root pages,
+  but the order of the rows in the sqlite&#95;master tables are different.
+
+  <li> <b>schema cookie</b> - the database schemas are compatible, but the 
+  schema cookie values ("PRAGMA schema&#95;version") are different.
+</ul>
+
+The final three problems in the list above can be fixed using the
+.shared-schema command. To modify such a database so that it can share a 
+schema with the main database, the following shell command is used:
+
+        .shared-schema fix <database-1> [<database-2>]...
+
+If a database can be modified so that it may share a schema with the main
+database opened by the shell tool, output is as follows:
+
+        Fixing <database>... <database> is compatible
+
+If a database does not require modification, or cannot be modified such that
+it can share a schema with the main database, the output of "fix" is identical
+to that of the "check" command.
+
 ## Implementation Notes
 
 A single Schema object is never used by more than one database simultaneously,

diff --git a/manifest b/manifest
index 0f1a6af2842e944da455f7341c2e44ed34bbfe01..5b13c039dfd5398370618439f5e2b5f93a3c8164 100644 (file)
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Add\snew\stest\sfile\sreuse5.test.\sFor\stesting\sthe\sshell\stool\s".shared-schema"\scommand.
-D 2019-02-26T16:13:43.604
+C Update\sdoc/shared_schema.md\sto\sdescribe\sthe\sshell\stool\s".shared-schema"\sdot-command.
+D 2019-02-26T16:36:21.259
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
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 F Makefile.in 56456706c4da271309914c756c9c8ea537685f1c79f8785afa72f968d6810482
@@ -39,7 +39,7 @@ F contrib/sqlitecon.tcl 210a913ad63f9f991070821e599d600bd913e0ad
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diff --git a/manifest.uuid b/manifest.uuid
index a2a150bb9810b7ede79eea51a1043b6837a8a3ea..ffe72040a1954b432460a455c9f127d35074fcbd 100644 (file)
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
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