index_details.h

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// index_details.h

#pragma once

#include "mongo/db/storage/mmap_v1/diskloc.h"

namespace mongo {

/* Details about a particular index. There is one of these effectively for each object in
   system.namespaces (although this also includes the head pointer, which is not in that
   collection).

   This is an internal part of the catalog.  Nothing outside of the catalog should use this.

   ** MemoryMapped in NamespaceDetails ** (i.e., this is on disk data)
 */
#pragma pack(1)
struct IndexDetails {
    DiskLoc head;

    /* Location of index info object. Format:

         { name:"nameofindex", ns:"parentnsname", key: {keypattobject}
           [, unique: <bool>, background: <bool>, v:<version>]
         }

       This object is in the system.indexes collection.  Note that since we
       have a pointer to the object here, the object in system.indexes MUST NEVER MOVE.
    */
    DiskLoc info;

    void _reset();
};
#pragma pack()

}  // namespace mongo